Express the function g in the form f°g.
g(x) = x²/x² - 3
a) f(x) = 1/x; g(x) = x² - 3
b) f(x) = x²; g(x) = 1/x - 3
c) f(x) = x² - 3; g(x) = 1/x
d) f(x) = 1/x - 3; g(x) = x²