Your Mother Helped You Start Saving $10 a Month Beginning

Your mother helped you start saving $10 a month beginning on your 5^thbirthday, which is on May 1^st. She always made you make your deposit on the first day of each month just to "start the month out right". Today, you turn 21 and have $6,984 in your account. What is the rate of return on your savings?

A) 13.62%
B) 13.68%
C) 13.75%
D) 13.81%
E) 13.86%