Joe wants to set one lump sum of money aside today to pay for his child's college education, which will occur in 15 years and cost $50,000.

Joe wants to set one lump sum of money aside today to pay for his child's college education, which will occur in 15 years and cost $50,000. If the current 15 year interest rate is 7%, then how much does Joe need to set aside today?

a. $18,122

b. $137,952

c. $3,333

d. $18,797