A loan is being repaid with 20 annual payments. The payments at the end of years 1, 3 ,5, ...19 are 1000. The payments at the end of year 2,4,6, ... 20 are 5000. The annual effective interest rate on the loan is 7.25%. Calculate the principal in the payment at the end of the 18th year. (Please provide the steps and calculations)

A. 4205.13

B. 4305.13

C. 4405.13

D. 4505.13

E. 4605.13