According to human capital theory, why is there a college wage premium?

A.When entering the labor market, college graduates are older than high school graduates, and older workers earn higher incomes than younger workers.

B.A college diploma is a signal that is less costly to acquire for high-skilled people than for low-skilled people.

C.In college, students acquire skills that are valuable to future employers.

D.In college, learn how to be away from their parents and mature, which increases their skills.