One Reason That College Graduates Earn Higher Wages Than Non-Graduates

One reason that college graduates earn higher wages than non-graduates is because college graduates

A) acquire additional skills to allow them to work in more industries than non-graduates.
B) always work in more dangerous jobs than non-graduates.
C) are always more intelligent than non-graduates.
D) are less equipped to deal with technological change, as their skills are technology-specific.