The graph of f(x) = 5x2 is shifted 6 units to the left to obtain the graph of g(x). Which of the following equations best describes g(x)?
a g(x) = 5x2 + 6
b g(x) = 5(x − 6)2
c g(x) = 5(x + 6)2
d g(x) = 5x2 − 6