Which of These Would Have a Negative Impact on the Rate

Which of these would have a negative impact on the rate of return on a student's investment in education?

A) The opportunity cost is low because of the student's low skill level at the time she entered school.
B) Many years of training are required to gain the necessary skills.
C) The student receives a scholarship that covers half of her tuition.
D) Free online textbooks become available as a substitute for purchased textbooks.