You want to build up an annuity which can pay you $5,000 per month for 25 years (= 300 months), when the monthly interest rate is .006 per month. You want the annuity to begin paying you after 15 years (= 180 months) of saving at an interest rate of .005. What must your monthly level of saving be, in order to carry out this plan?

a. $2389.26

b. $2856.91

c. $3417.96

d. None of these