The function $f : \mathbb { R } \to \left[ - \frac { 1 } { 2 } , \frac { 1 } { 2 } \right]$ defined as $f ( x ) = \frac { x } { 1 + x ^ { 2 } }$, is:\\
(1) Surjective but not injective\\
(2) Neither injective nor surjective\\
(3) Invertible\\
(4) Injective but not surjective