# The set of points, where $f(x) = \frac{x}{1 +|x|}$ is differentiable, is :
( A ) $(-\infty, -1) \cup (-1, \infty)$
( B ) $(-\infty, 0) \cup (0, \infty)$
( C ) $(-\infty, \infty)$
( D ) $(0, \infty)$