At the beginning of each month, $200 is deposited into a retirement fund that earns 6% annual interest, compounded monthly. How much is in the account right after the last deposit if deposits run for 10 years?

1. An annuity of equal deposits with monthly compounding is valued with the geometric series formula. 2. The monthly rate is 6% / 12 = 0.5%, so the growth factor is r = 1.005. 3. Ten years of monthly deposits means n = 120 deposits of a_1 = $200. 4. Apply S_n = a_1(1 - r^n)/(1 - r) with these values. 5. Compute 1.005^120, which is approximately 1.8194. 6. S_120 = 200(1 - 1.8194)/(1 - 1.005) = 200(0.8194/0.005). 7. That equals 200 x 163.88, or about $32,776 in the account. 8. Option A, $24,000, is the bare total of deposits, 120 x $200, with no interest at all. 9. Option C uses a 3% annual rate, and option D compounds the full 6% every month, both misreading the rate per period. _Source: OpenStax Algebra and Trigonometry (CC BY 4.0), Ch 13 "Sequences, Probability and Counting Theory", section 13.4 SERIES AND THEIR NOTATIONS_