If an economist's job paid $50,000 a year 10 years ago, how would understanding the present value and future value of money help explain the difference in the pay rate for the same job today?

A. It would predict the future pay rate in 10 more years.
B. It would guarantee a fixed pay rate increase each year.
C. It would justify why the pay rate has more than doubled.
D. It would calculate the pay rate adjusted for economic changes.