Main memory of computer is—

Explanation:

Option (a) Internal is the correct answer. Main memory, primarily RAM, is considered internal memory because it is located directly on the motherboard and is directly accessible by the CPU. Option (b) External memory refers to storage devices connected externally (e.g., USB drives). Option (d) Auxiliary memory is another term for secondary storage, which can be internal (like an HDD) but is not the 'main' memory in the context of direct CPU processing. Therefore, (c) and (e) are incorrect.