Derek purchased a 2010 model sedan for $21,000. The dealership offered him a $149/month payment plan for 60 months, at the end of which the unpaid balance will be due. If the interest rate is 6%, find the balloon payment due at the end of 60 months.

a. $19,726.27
b. $17,930.12
c. $15,000
d. $14,448