The number of teams who entered in a 3-on-3 charity basketball tournament can be modeled by function t, where x is the number of years since the tournament first started.

t(x)=4x+24

the entry fee paid by each team to enter the tournament can be modeled by function f, where x is the number of years since the tournament first started.

f(x)=5x+45

which function, r, best represents the total entry fees collected in the xth year since the tournament first started?

a. r(x)=20x^2+300x+1,080

b. r(x)=9x+69

c. r(x)=9x^2+29x+69

d. r(x)=20x^2+1,080