ASAP please! I have to get this done to get my grades up!

If f(x) = x2 - 3x + 5 and g(x) = 3x. Find the product of the functions.

A) (f · g)(x) = x2 + 5
B) (f · g)(x) = 3x2 - 9x + 15
C) (f · g)(x) = 3x2 - 6x + 15
D) (f · g)(x) = 3x3 - 9x2 + 15x