You have been asked to use a 25 bit subnet mask to segment the following network block:
209.18.12.0.
How many usable will there be per subnet?（）

A..65 through .126
B..64 through .127
C..66 through .128
D..65 through .127

A..24 through .48
B..24 through .32
C..25 through .30
D..35 through .31

A.10 hosts
B.14 hosts
C.12 hosts
D.16 hosts