Choose legitimate reasons why the rdbms caches data and other resources you may choose more than one answer.

a. the cache speeds up data update operations.
b. the cache speeds up data insert and data delete operations.
c. once an execution plan is made for a query, if the query is executed again, the rdmbs can retrieve the plan from the cache rather than recreate it.
d. once a data page is read from disk, caching it allows other queries to access its data from the cache rather than having to re-read from disk.