Who Is Likely to Earn a Higher Income,dentists or Dental

Who is likely to earn a higher income,dentists or dental hygienists,and why?

A) dental hygienists, because their education is less expensive
B) dentists, because their education is less expensive
C) dental hygienists, because their education is more expensive
D) dentists, because their education is more expensive
E) neither, because they usually earn the same wage rate