Which of the following memories must be refreshed many times per second?

Explanation:

Option (d) Dynamic RAM (DRAM) is the correct answer. DRAM stores data in capacitors, which slowly leak charge, requiring them to be constantly refreshed (recharged) many times per second to prevent data loss. Option (a) EPROM (Erasable Programmable Read-Only Memory) and (b) ROM (Read-Only Memory) are non-volatile memories and do not require refreshing. Option (c) Static RAM (SRAM) is volatile but uses latches to store data, which do not require refreshing, making it faster and more expensive than DRAM.