Explanation:

Microcomputer:
A microcomputer is a type of computer that has a microprocessor as its central processing unit (CPU). It is a small, low-cost computer designed for individual use. Examples of microcomputers include personal computers (PCs), laptops, tablets, and smartphones.

Minicomputer:
A minicomputer, also known as a midrange computer, is a type of computer that is smaller and less powerful than a mainframe computer but larger and more powerful than a microcomputer. It can support multiple users and handle more complex tasks. Minicomputers were commonly used in the 1960s and 1970s but have been largely replaced by microcomputers and servers.

Supercomputer:
A supercomputer is a type of computer that is designed to perform complex calculations at very high speeds. It is typically used for scientific and engineering applications that require a large amount of processing power. Supercomputers are among the fastest and most powerful computers in the world.

Digital computer:
A digital computer is a computer that operates using digital data and performs calculations using digital circuits. It uses binary digits (0s and 1s) to represent and process information. Most modern computers, including microcomputers, minicomputers, and supercomputers, are digital computers.

All of the above:
The odd one out in this list is "All of the above." This is because microcomputers, minicomputers, supercomputers, and digital computers are all types of computers. The other options (a, b, c, d) represent specific categories or types of computers.

Therefore, the correct answer is option 'D' - All of the above.