Which memory type is typically used to store program instructions that do not change?

The choice of ROM as the correct answer is rooted in its primary function within a computer system. ROM, or Read-Only Memory, is designed to store firmware and permanent instructions that are essential for the initial booting of the system and for basic hardware functions. Its contents are not meant to be altered frequently, making it ideal for storing unchangeable program instructions that are critical for the system's operation.

In contrast, RAM (Random Access Memory) is a volatile memory type used for temporary storage of programs and data that are currently in use. It allows for quick read and write access, but all data is lost when the power is turned off, which does not suit the needs for storing permanent instructions.

Similarly, an SSD (Solid State Drive) is a type of storage device used for long-term data storage and can hold changing data. It allows for fast access but is primarily used for storing files, applications, and operating system data that may change over time.

Cache memory serves as a high-speed storage area for frequently accessed data and instructions to improve processor efficiency, but like RAM, it is volatile and does not serve the function of storing unchangeable program instructions.

Therefore, ROM is the optimal choice for this question, as it fulfills the requirement