The correct answer is D. Buffer.
A buffer is a temporary storage area used to hold data while it is being transferred from one device to another. It can also be used to store data that is waiting to be processed. Buffers are often used in computer systems to improve performance by reducing the number of times that data needs to be read from or written to a slower device.
PROM (Programmable Read-Only Memory) is a type of memory that can be programmed once and then can only be read. It is often used to store firmware, which is the software that controls the hardware in a device.
SAM (Static RAM) is a type of memory that retains its contents even when the power is turned off. It is often used to store data that needs to be accessed quickly, such as the contents of the screen or the keyboard buffer.
Scratchpad storage is a small amount of high-speed memory that is used to store data that is being actively used by the processor. It is often used to store intermediate results of calculations or to hold data that is waiting to be transferred to or from another device.
E is not the correct answer because it is not a type of memory.