Which two measures can you take to reduce input/output (I/O) as a bottleneck?

Which two measures can you take to reduce input/output (I/O) as a bottleneck? (Choose two.)

A.
Install a single-bus adapter.

B.
Tune the application and memory.

C.
Balance I/O across drives and controllers.

D.
Place redo logs and datafiles on the same disk.

E.
Maximize the number of stripe columns in RAID 5.