If Supply Shifts Were the Primary Cause Behind the Increasing

If supply shifts were the primary cause behind the increasing wage gap between highly-educated and less-educated workers then

A) both supply curves must shift in the same direction.
B) the employment of less-educated workers would increase relative to the employment of college-educated workers.
C) the employment of less-educated workers would decrease relative to the employment of college-educated workers.
D) the relative employment of the two groups would not change.