The correct answer is ROM.

• Primary memory is computer memory that is accessed directly by the CPU.
• This includes several types of memory, such as cache and system ROM.

• Secondary memory is a memory that is not accessed directly by the CPU.
• Secondary memory refers to storage devices, such as hard drives and solid-state drives.

•  It may also refer to removable storage media, such as USB flash drives, CDs, and DVDs.

• Key differences between primary and secondary memory are-
  1. Primary memory is called internal memory whereas Secondary memory is also known as auxiliary memory. 
  2. Primary memory can be accessed by the data bus whereas Secondary memory is accessed by I/O channels.
  3. Primary memory data is directly accessed by the processing unit whereas Secondary memory data cannot be accessed directly by the processor.
  4. Primary memory is costlier than secondary memory.
  5. Primary memory is both volatile & nonvolatile whereas Secondary memory is always a non-volatile memory.