One or Two Generations Ago, Fewer Canadians Completed Post- Secondary

One or two generations ago, fewer Canadians completed post- secondary training and education. One explanation for this is

A) a decrease in demand for more education in recent years.
B) that the opportunity cost of port- secondary education has increased.
C) a negative relationship between the acquisition of human capital and overall earnings.
D) the relative wage of more highly educated people has increased in recent years.
E) wage differentials due to formal education have diminished over time.