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.

Phil has more human capital relative to Bill.

Phil has less human capital relative to Bill.

Phil receives a higher wage to compensate for the disagreeable nature of business travel.

Bill's lower salary supports the signaling theory of education.