What is the purpose of cache on the CPU?

Question $9$ options:

Cache is how the CPU access system memory for processing complex requests.

Cache is an encrypted portion of the CPU and where encryption keys are processed for access requests.

Cache stores information and allows for quick re$-$use making the CPU much more efficient.

Cache is how the CPU buys time for processing for the system.

Cache includes a map of all the potential functions a CPU can handle and is how information is processed.