Which memory is nonvolatile and may be written only once?

The correct answer is B. EE-ROM.

• RAM (Random Access Memory) is a volatile memory, which means that it loses its contents when the power is turned off.
• EE-ROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that can be erased and reprogrammed electrically.
• PROM (Programmable Read-Only Memory) is a non-volatile memory that can be programmed once, but cannot be erased or reprogrammed.

EE-ROM is a type of non-volatile memory that can be erased and reprogrammed electrically. It is often used in embedded systems and other applications where data needs to be stored permanently, but may need to be updated occasionally. EE-ROM is typically more expensive than other types of non-volatile memory, such as flash memory, but it offers greater durability and reliability.