ANS:A - Operation code

The part of a machine-level instruction that tells the central processor what has to be done is called the operation code (opcode). The opcode specifies the particular operation or action that the processor needs to perform, such as addition, subtraction, loading data from memory, or storing data to memory.

The opcode is a binary code that represents the specific operation to be executed by the processor. It is usually located in the instruction's binary representation at a specific position, allowing the processor to easily identify and interpret the desired operation.

In summary, the operation code (opcode) is the part of a machine-level instruction that informs the central processor about the specific action or operation it needs to perform.