In an Economy in 2011, 3 Million People Had Full-Time

In an economy in 2011, 3 million people had full-time managerial and professional jobs that paid an average of $800 a week. At the same time, 1 million people had full-time sales positions that paid an average of $530 a week. Managers and professionals are paid more than salespeople because

A) the supply curve of managers and professionals lies above that of salespeople.
B) the demand curve for managers and professionals lies above that of salespeople.
C) managers and professionals have a a higher value of marginal product.
D) the typical manager or professional has incurred a higher cost of education.
E) all of the above