Let \( f : R \to R \) be defined as \( f(x) = x - 1 \) and \( g : R - \{ 1, -1 \} \to R \) be defined as \( g(x) = \frac{x^2}{x^2 - 1} \). Then the function \( fog \) is:
one-one but not onto
onto but not one-one
both one-one and onto
neither one-one nor onto