The total surface area of a cylinder with height 5 in. is given by the function g(x) = 2πx2 + 10πx, where x is the radius, and the function f(x) = 10πx gives the surface area of the side of the cylinder. Which combined function gives the total surface area of the two bases of the cylinder? A. f + g B. f – g C. g – f D. f · g