A sports club plans to have its lawn mowed. The cost of mowing x square feet of lawn is given by the function f(x) = 0.04x + 3.5, where f(x) represents the cost in dollars. The total area that needs to be mowed is given by the function g(x) = 12x.

Which function best describes C(x), the total cost of mowing the lawn of the sports club?

A) C(x) = 0.48x + 3.5x
B) C(x) = 0.48x2 + 3.5
C) C(x) = 0.48x2 + 42x
D) C(x) = 0.48x2 + 42