Ans: A
$\begin{array}{rcl}
\dfrac{1}{x+1} – \dfrac{1}{x-1} & = & \dfrac{(x-1) – (x+1)}{(x+1)(x-1)} \\
& = & \dfrac{-2}{x^2-1} \\
& = & \dfrac{2}{1-x^2}
\end{array}$
$\begin{array}{rcl}
\dfrac{1}{x+1} – \dfrac{1}{x-1} & = & \dfrac{(x-1) – (x+1)}{(x+1)(x-1)} \\
& = & \dfrac{-2}{x^2-1} \\
& = & \dfrac{2}{1-x^2}
\end{array}$
