A class of random access memory that requires periodic servicing in order for the contents to remain valid is

ANS:B - Dynamic RAM

DRAM : is a memory must be constantly refreshed (reenergized) to preserve its contents. RAM (random-access memory) is sometimes referred to as DRAM. It is a type of RAM that stores each bit of data in a separate capacitor within an integrated circuit. The capacitor can be either charged (represents a binary bit 1) or discharged (represents a binary bit 0).