A PC is a general-purpose microprocessor-based computing system.

Computers are fundamentally designed to perform several core operations. These include: 1. **Arithmetic operations**: These are mathematical calculations such as addition, subtraction, multiplication, and division. The Arithmetic Logic Unit (ALU) within the CPU is responsible for these. 2. **Logical operations**: These involve comparisons and decision-making, such as determining if one value is greater than, less than, or equal to another, or performing Boolean operations like AND, OR, and NOT. These are also handled by the ALU. 3. **Storage and retrieval of data**: This operation involves writing information to memory (RAM, hard drives, etc.) and reading it back when needed. This is crucial for programs to access instructions and manipulate data. Since a computer must perform all of these types of operations to function effectively, 'All of the above' is the correct answer.

OMR stands for Optical Mark Recognition. It is a technology that detects the presence or absence of a mark in a designated area on a document, such as a bubble or checkbox. This technology is widely used in examinations to rapidly and accurately score multiple-choice answer sheets, surveys, and other forms where data is captured through human-filled marks. It automates the process of data entry and evaluation, significantly reducing the time and potential for error compared to manual methods.

E-business covers all aspects of buying and selling goods or services online.

A mainframe computer is the most appropriate choice for a university's central system due to its unparalleled capacity for processing massive volumes of transactions, managing extensive databases that are critical for student records, and ensuring continuous operation with high reliability and stringent security. While supercomputers are powerful, they are designed for complex scientific calculations and simulations, not high-volume transactional data. Minicomputers were an intermediate class of computer but lack the scale for a large university's central system. A distributed network of personal computers (microcomputers) would struggle with the centralized control, security, and transaction integrity required for such a critical application, often leading to data inconsistencies and security vulnerabilities.

Spreadsheet programs, such as Microsoft Excel, Google Sheets, or LibreOffice Calc, are designed to manage and organize data efficiently. Their core organizational principle involves a grid structure where data is entered into individual 'cells.' These cells are formed by the intersection of horizontal 'rows' (typically numbered) and vertical 'columns' (typically lettered). This tabular arrangement makes it exceptionally well-suited for numerical calculations, data analysis, sorting, filtering, and creating various types of charts and graphs based on the structured data.

The key strengths of a computer are its speed, accuracy, and memory capacity.

A pixel, an abbreviation for 'picture element,' is the smallest addressable point in a raster image or on a digital display. Each pixel carries information about color and intensity, and when arranged in a grid, these individual elements combine to form the complete visual content. Therefore, it is the fundamental, indivisible unit of a digital image or display. Option A correctly identifies this role. Option B, 'A unit quantifying data storage within a computer system,' describes memory units like bytes or gigabytes, not pixels. Option C, 'A component in a digital camera that converts light into electrical signals,' refers to a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor, which captures light but is not the pixel itself in the resulting image. Option D, 'A data compression technique specifically designed for visual content,' describes algorithms like JPEG or PNG, which are used to reduce file sizes but do not define what a pixel is.

Digital devices process and display information using discrete, distinct values, most commonly binary digits (0s and 1s). These values are separate and countable. * **Option A (Analog thermometer):** A mercury column thermometer represents temperature through the continuous expansion or contraction of mercury, showing a continuous range of values. This is an analog representation. * **Option B (Traditional phonograph):** A phonograph needle translates continuous physical variations in the record's grooves into continuous electrical signals, which are then converted into sound waves. This is an inherently analog process. * **Option C (Car's speedometer):** An analog speedometer uses the continuous rotation of a needle to indicate speed, moving smoothly across a scale. This is an analog representation. * **Option D (Modern smartphone displaying a clock):** A smartphone is a digital device. When it displays a clock, it uses digital circuitry to calculate and present time using discrete numerical digits (e.g., '10:30'). Each digit is a distinct value, making it a digital representation of time.

In computer science and digital electronics, a nibble (sometimes spelled 'nybble') is a unit of data comprising 4 bits. This grouping is particularly useful because 4 bits are precisely what is needed to represent a single hexadecimal digit (since 2^4 = 16, allowing values from 0 to F). For example, the binary sequence '1011' (which is 11 in decimal) perfectly corresponds to the hexadecimal digit 'B'. A nibble is also exactly half of a standard 8-bit byte. Therefore, options A, C, and D are incorrect as they misrepresent the defined size of a nibble.