please give explanation for the answer

Question: Gotham City issued a purchase order for supplies with an estimated cost of $5,000. When the supplies were received, the accompanying invoice indicated an actual price of $4,950. What amount should Gotham debitor credit to the budgetary fund balance account after the supplies and invoice were received? A $50 Credit B. $50 Debit C. $4.950 Debit D. 55.000 Debit