14. Given that the announced mortgage interest rates of three banks A, B and Care 5%, 6% and 7% respectively, and the financing cost is 7.5%, 8% and 90% respectively, assuming that the housing market crisis occurs, the house price generally falls by 15% to 18%, please explain why the housing interest rate is directly proportional to the financing cost, and then explain which bank will face the heaviest credit risk and its reasons