In the context of computer systems, what does the term "cache invalidation" refer to?
A. The process of removing outdated or obsolete data from a cache to ensure that the system retrieves the most current information.
B. The act of modifying data to correct errors before storing it in a cache.
C. The practice of encrypting cached data to enhance security and prevent unauthorized access.
D. The procedure of backing up cached data to an external storage device to prevent data loss.