What is the purpose of the least recently used (LRU) algorithm?

• A. Sort items by usage
• B. Encrypts data
• C. Generates random data for cache
• D. Cache eviction policy removing the least recently accessed items

Answer: (D)

The idea behind LRU is how a cache decides which item to remove when it runs out of space. It works by assuming that data touched recently will be needed again soon, while data that hasn’t been used for a long time is less likely to be needed. So when the cache is full and a new item needs to be loaded, the least recently accessed item—the one that has not been used for the longest time—gets evicted to make room. In practice, implementations track recency with a timestamp or use a data structure that moves the most recently used to one end and the least recently used to the other; eviction happens at the other end. This approach helps keep data that’s likely to be reused in fast storage, improving overall performance for typical access patterns. Other options don’t fit because encryption has nothing to do with deciding which cached item to discard, generating random data isn’t about managing existing cached items, and simply sorting items by usage isn’t itself an eviction rule.