A loan taken out at an interest rate of 21%, monthly capitalization, must be repaid using 120 constant monthly end-of-period payments. When he makes his 40th payment, the borrower pays an additional sum of $ 6,000. The remaining monthly payments are then reduced to $ 759.77. What was the value of the initial monthly payment?

A. $ 834.77

B. $ 897.30

C. $ 899.70

D. $ 864.60

E. $ 794.70