Which two statements are true about a buffer cache?

Which two statements are true about a buffer cache?

A.
When a buffer is read from a buffer cache, it may be inconsistent and require undo data to make it
consistent.

B.
A buffer cache stores copies of data blocks from all files of the database.

C.
Buffer access is kept efficient by maintaining a least recently used (LRU) list for dirty and clean buffers.

D.
A buffer cache always resides completely in System Global Area (SGA).

E.
A buffer cache contains exactly three pools: default, keep, and recycle pool.