Name the components labeled #3 and #4 in exhibit the above displays the basic architecture of a Symmetrix?

A.
#3 = Front-end Channel Director
#4 = Cache
B.
#3 = Front-end Channel Director
#4 = Back-end Disk Director
C.
#3 = Cache
#4 = Disk Drive
D.
#3 = Cache
#4 = Back-end Disk Director