Choose the statement that best expresses the central idea of this selection.
A
Some military schools continued to exclude women long after others graduated their first female classes.
B
Since World War II, gender discrimination in the U.S. military has declined to almost imperceptible levels.
C
Women have long-served the U.S. military in crucial roles, but obstacles to equal opportunity remain.
D
More than 10,000 women served in the Vietnam War, but little is known about their service in this conflict.