Which of the following is equivalent to \ac1x−1−\ac1x+1\ac{1}{x-1} - \ac{1}{x+1}\ac1x−1−\ac1x+1?
\ac2x2−1\ac{2}{x^2 - 1}\ac2x2−1
\ac2xx2−1\ac{2x}{x^2 - 1}\ac2xx2−1
\ac−2x2−1\ac{-2}{x^2 - 1}\ac−2x2−1
000