The return on investment (roi) from education is typically the highest for D. someone with a 4-year (bachelor's) degree. This is because this student has the most to pay, he or she has been studying for 4 years in high school, and then at least 4 more years in college. Thus, he has at least 4 years to pay for his studies (given that he doesn't have to pay for high school education), which is why his roi is higher than the other three options.
