The algorithm which replaces the block which has not been referenced for awhile is called ………ans.LRUOptimal Page ReplacementRandom ReplacementFIFO

The algorithm that replaces the block which has not been referenced for a while is called LRU (Least Recently Used) Page Replacement.

Explanation:

1. LRU (Least Recently Used): This algorithm keeps track of page usage over time and replaces the page that has not been used for the longest period. It is based on the principle that pages used recently will likely be used again soon.

2. Optimal Page Replacement: This approach replaces the page that will not be used for the longest period in the future, but it requires future knowledge of page requests, making it impractical in many real-world applications.

3. Random Replacement: This method selects a page to be replaced randomly, which can lead to poor performance since it does not consider page usage patterns.

4. FIFO (First-In-First-Out): This algorithm replaces the oldest page in memory, which does not always yield good performance since older pages may still be in use.

In summary, LRU is designed specifically for optimizing page replacement by focusing on the recency of use, making it the best choice for situations where pages need to be managed efficiently.