Which of the following can you do to express an IPv6 address as efficiently as possible?

Which of the following can you do to express an IPv6 address as efficiently as possible?
(Select 2 choices.)

A.
Replace every four-character group of zeros with double colons.

B.
Remove leading and trailing zeros from each four-character group.

C.
Remove only leading zeros from each four-character group.

D.
Remove only trailing zeros from each four-character group.

E.
Replace only one four-character group of zeros with a double colon.

F.
Replace one or more contiguous four-character groups of zeros with a double colon.