The correct answer is option C) Operation code.

Operation code, also known as opcode, is the instruction code used in machine or assembly language that specifies the basic operations of the CPU (Central Processing Unit). It is a fundamental part of the instruction set architecture of a computer.

Here is a detailed explanation:

1. Machine Code:
Machine code is a low-level programming language that consists of binary instructions executed directly by the CPU. Each instruction is represented by a specific pattern of 0s and 1s. Machine code is specific to the hardware architecture of the computer and is not easily human-readable.

2. Instruction Code:
Instruction code is a broader term that encompasses both machine code and assembly code. It refers to the set of instructions that a computer can execute. These instructions specify the operations that the CPU should perform, such as arithmetic calculations, data movement, and control flow.

3. Operation Code (Opcode):
The operation code is the part of the instruction that specifies the operation to be performed by the CPU. It determines the type of operation, such as addition, subtraction, multiplication, or branching. The opcode is usually represented by a binary or hexadecimal value.

4. Assembly Code:
Assembly code is a low-level programming language that uses mnemonics to represent machine instructions. It is a human-readable representation of the machine code. Each assembly instruction corresponds to a specific machine instruction and includes an opcode along with optional operands.

5. Language Code:
Language code is a term that is not directly related to the instruction code used in machine or assembly language. It could refer to a programming language such as C, Python, or Java, which are higher-level languages that provide more abstraction and easier programming compared to machine or assembly language.

In summary, the instruction code used in machine or assembly language that specifies the basic operations of the CPU is the operation code (opcode). It is a fundamental part of the instruction set architecture and determines the type of operation to be performed by the CPU.