The disadvantage of dynamic RAM over static RAM is

higher power consumption
variable speed
need to refresh the capacitor charge every once in two milliseconds
higher bit density E. None of the above

The correct answer is C. need to refresh the capacitor charge every once in two milliseconds.

Dynamic RAM (DRAM) is a type of random-access memory that stores each bit of data in a separate capacitor. The capacitors can hold a charge for a short period of time, but they eventually lose their charge and need to be refreshed. This is done by reading the data from the capacitor and then writing it back to the capacitor. The refresh process needs to be done every few milliseconds, which is one of the main disadvantages of DRAM.

Static RAM (SRAM) is a type of random-access memory that stores each bit of data in a flip-flop. Flip-flops are electronic circuits that can store data indefinitely without needing to be refreshed. This makes SRAM faster and more power-efficient than DRAM. However, SRAM is also more expensive than DRAM.

A. higher power consumption: DRAM does require more power than SRAM, but this is not the main disadvantage of DRAM. The main disadvantage of DRAM is that it needs to be refreshed every few milliseconds.

B. variable speed: The speed of DRAM can vary depending on the type of DRAM and the manufacturer. However, the speed of DRAM is not the main disadvantage of DRAM. The main disadvantage of DRAM is that it needs to be refreshed every few milliseconds.

D. higher bit density: DRAM can have a higher bit density than SRAM. This means that DRAM can store more data in the same amount of space. However, the higher bit density of DRAM is not the main advantage of DRAM. The main advantage of SRAM is that it does not need to be refreshed.