To solve this question, the user needs to know the financial functions in Excel and their respective parameters. The user must be familiar with the concept of a loan and its components, such as the principal, interest rate, and term.

Option A: The Pay function is not a recognized financial function in Excel. Therefore, option A is incorrect.

Option B: The Pmt function returns the periodic payment required to pay off a loan, given the interest rate, number of payments, and loan amount. This is the correct function to use for calculating the monthly payments of a loan. Therefore, option B is the correct answer.

Option C: The FV function is used to calculate the future value of an investment or loan, given the interest rate, number of payments, and periodic payment amount. Therefore, option C is incorrect.

Option D: The FV function is used to calculate the future value of an investment or loan, given the interest rate, number of payments, and present value. Therefore, option D is incorrect.

Option E: None of the above functions exist in Excel. Therefore, option E is incorrect.

The answer is: B. Pmt (Rate, Nper, PV)