Marysa invested $1,000 at the beginning of every 3 months in an RRSP for 18 years. For the first 11 years, it earned interest at a rate of 4.8% compounded quarterly, and for the next 7 years, it earned interest at a different rate. What is the total amount in the RRSP after 18 years?
a) $68,234.09
b) $71,549.87
c) $65,789.23
d) $74,321.45