Bill and Phil Are Identical Twins Who Attended Grammar School

Bill and Phil are identical twins who attended grammar school through college together.Bill took a job as an engineer who does not have to travel out of the state.Phil took a job as an engineer who must travel out of state once a week.Bill earns $105,000 a year,and Phil earns $185,000 a year.Select the best explanation for this wage difference.

A) Phil has more human capital relative to Bill.
B) Phil has less human capital relative to Bill.
C) Phil receives a higher wage to compensate for the disagreeable nature of business travel.
D) Bill's lower salary supports the signaling theory of education.