Answer : 2. "ROM and RAM"
Explanation :

Answer: B) ROM and RAM Explanation: The main memory is defined as the central storage in a computer. (noun) An example of the main memory is where programs and data are kept when the processor is actively using them.   The main storage region of a computer, to which the central processor has immediate or direct access is of two kinds. They are :: RAM -- Random Access Memory ROM -- Read Only Memory.