Answer:
Option A - 13.6%
Step-by-step explanation:
Given : Chelsea made monthly payments for four years before her $13,440 loan was paid off. The loan had an interest rate of 5.86%, compounded monthly.
Chelsea paid $156.60 in service charges.
To find : Percentage of the total cost of the loan did her finance charges comprise?
Solution : First we find the monthly payment
Formula of monthly payment
Monthly payment,
Discount factor
Where, Amount = $13,440
Rate r= 5.86%=0.0586 compounded monthly
Time = 4 years
Now, put all the values we get,
Monthly payment,
Monthly payment is $314.77
For 4 years or 48 months
Payment is 
Total amount = Payment - Amount
Total amount = 15108.96 - 13440
Total amount = 1668.96
Cost of loan is total amount with service charges is
⇒1668.96+156.60 = $1825.56
Total cost of the loan did her finance charges comprise



Total cost in percentage 
Approximately,Total cost of the loan did her finance charges comprise is 13.6%
Therefore, Option A is correct - 13.6%