The local recreation center charges members a registration fee and a separate monthly membership fee. The equation of the function given models the total fee, f(x), in dollars, that a person pays for x months of membership.

f(x)=25x+50

What does the number 25 represent?

A. the initial registration fee

B. the number of months that a person is a member

C. the monthly membership fee

D. the total amount that a member pays in fees