The smallest unit of data that can be transferred between the cache and main memory is called.

• A. Cache Block Size
• B. Word Size
• C. Memory Page
• D. Cache Line Size

Answer: (A)

Data moves between cache and main memory in fixed-size chunks. This smallest transferable chunk is what we call a cache line, often referred to as a cache block as well. The size of that chunk is the cache block size (or cache line size). In this context, the term that names the unit being transferred is the cache block, so describing it as the cache block size fits what the question asks. The other options don’t describe the transferable unit: word size is the processor’s data width, memory page relates to virtual memory management, and cache line size is about the amount of data in the line rather than naming the unit itself.