Answer:
A. missing a loan payment
Explanation:
Whenever someone wish to apply a loan, lenders would consider his/her credit scores when analyzing the application. A good credit score would increase his/her chance to be qualified for the loan. The higher the score qualifies you for a fair interest rates, and also it would reduce the perceived risk.
Considering the question, missing a loan payment would definitely affect his credit score negatively. It would affect the interest rate, loan terms and credit limit.