Which of the following is a characteristic of read-only memory (ROM)?

Read-only memory (ROM) is specifically designed to retain data even when the computer is powered off, which makes it a non-volatile form of storage. This characteristic is vital because it allows firmware and critical system instructions to be stored permanently, ensuring that the computer can boot up and function correctly after being turned off. Unlike volatile memory, such as RAM, which loses all stored data when the power is disconnected, ROM maintains its contents, making it an essential component for storing system firmware and boot processes. This ensures that the computer has the necessary instructions to start up and operate properly each time it is powered on.

The other options do not accurately describe ROM; it cannot be modified easily by users, it is not faster than RAM since RAM is designed for speed in active processes, and it is definitely not volatile since that would contradict its fundamental purpose.