Explanation:

Memory in a computer system refers to the storage and retrieval of information. It can be categorized into different types based on its purpose and functionality. However, not all components associated with a computer system are considered forms of memory.

a) Instruction Cache:
- The instruction cache is a type of memory that stores frequently accessed instructions from the main memory.
- It is a high-speed cache memory located close to the CPU, designed to reduce the time taken to fetch instructions.
- The purpose of the instruction cache is to improve the overall performance of the system by providing faster access to frequently used instructions.

b) Instruction Register:
- The instruction register is a component within the CPU that holds the current instruction being executed.
- It is a temporary storage location used by the CPU to fetch and decode instructions.
- The instruction register plays a crucial role in the instruction cycle of a CPU, which includes fetching, decoding, executing, and storing instructions.

c) Instruction Opcode:
- This option is incorrect as the instruction opcode is actually a part of the instruction itself, not a form of memory.
- Opcode stands for "operation code" and represents the specific operation or instruction that needs to be executed by the CPU.
- It is typically represented by a binary code and provides information about the specific operation to be performed.

d) Translation Lookaside Buffer:
- The translation lookaside buffer (TLB) is a type of cache memory that stores recently used virtual-to-physical address translations.
- It is used to improve the efficiency of memory access by reducing the time taken to translate virtual addresses to physical addresses.
- The TLB is part of the memory management unit (MMU) and helps in the translation of virtual memory addresses to physical memory addresses.

In summary, the option 'c) Instruction Opcode' is not a form of memory. Instead, it represents the specific operation or instruction within an instruction and is used by the CPU to execute the appropriate action.