What are the three main cycles that the CPU goes through?

The correct answer is based on the fundamental operations of a CPU during instruction execution, known as the fetch-decode-execute cycle.

The fetch phase involves the CPU retrieving an instruction from memory, specifically from the address indicated by the program counter. This instruction is then loaded into the instruction register.

In the decode phase, the CPU interprets the fetched instruction, determining what operation is to be performed and identifying the operands (the data or addresses involved in the operation). This step often involves translating the binary instructions into a format that the CPU can understand.

Finally, in the execute phase, the CPU performs the operation as instructed, which could involve arithmetic or logical calculations, moving data from one place to another, or interacting with input/output devices.

This cycle is crucial for the CPU's functionality, as it defines how instructions are processed sequentially. The other options present different combinations of actions that do not accurately represent the established cycle of instruction processing in a CPU. For example, while 'retrieve, process, store' might suggest general operations, it does not explicitly capture the decoding step and its importance in interpreting instructions.