Which of the following is true regarding the earnings of attractive versus unattractive workers?
a. Attractive people tend to earn less because attractive people are viewed as shallow and more self-absorbed and, therefore, as less productive.
b. Attractive people tend to earn less because attractive people usually have less human capital.
c. Attractive people tend to earn more because they may actually have a larger value of marginal product.
d. Attractive people tend to earn more because attractive people usually have greater human capital.