Final answer:
To bill Carol, add the copayment to the MFS amount ($140 + $14).
Step-by-step explanation:
To calculate how much to bill Carol, we need to determine the allowable amount and her copayment percentage. The MFS (Medicare Fee Schedule) allows $140 for the treatment. Carol's copayment is 10%.
First, find 10% of $140 which is $14. This is the amount Carol will have to pay.
To calculate the total bill, add the copayment to the MFS amount. Bill = MFS + Copayment = $140 + $14 = $154.
Therefore, the correct answer is $154.