Answer: (iv) DRAM (2 Marks)

Correct choice is (iv) DRAM — Dynamic RAM.

• DRAM stores bit as charge on a capacitor + transistor (1T1C). It is volatile, needs periodic refresh (every ~64ms) due to leakage, but is very dense and cheap → used as main memory.
• Contrast: SRAM uses 6T flip-flop, no refresh, faster but larger/costlier (cache); ROM/EEPROM are non-volatile.
• Hence for high-capacity main memory the technology referred to is DRAM — option (iv).