Which subnet mask should you select?

Your company has a remote office that contains 600 client computers on a single subnet. You need to select a subnet mask for the network that will support all of
the client computers. The solution must minimize the number of unused addresses. Which subnet mask should you select?

A.
255.255.252.0

B.
255.255.254.0

C.
255.255.255.0

D.
255.255.255.128