Step-by-step Solution:

The correct answer is:
B. Locality of reference
Explanation:
Cache memory is highly effective due to the principle of locality of reference, which states that:
1. Temporal Locality: Recently accessed data is likely to be accessed again soon.
2. Spatial Locality: Data located near recently accessed memory locations is likely to be accessed soon. These principles allow cache memory to store frequently used data and instructions, making subsequent accesses faster and improving overall performance.