Mark purchased a house for $850,000. He paid 23% as a down payment and financed the balance with a 30-year amortized loan at a 6.25% interest rate. His monthly payments will also include property taxes ($8,500 per year) and hazard insurance ($9,780 for a three-year policy). If the principal amount on his first monthly payment is $621.01, what will be the total amount of his first monthly payment?

a. $6,437.32

b. $4,480.83

c. $4,026.45

d. $5,009.85