I need help! And is the sign of P positive or negative

Question 23 of 28 What are the units of P' (t)? The units are Which of the following is the best explanation of the practical meaning of P' (t)? O It is the annual payment on a t year mortgage. O It is the change in the monthly payment if the mortgage term were to be increased from t years to t + 1 years. It is the amount by which this month's payment in year t is different from this month's payment in year t + 1. It is the additional payment if the mortgage continues for t more years. It is the rate at which the payment in year t increases as interest rates increase