If $f ( x ) = \cos ( x ) - 1 + \frac { x ^ { 2 } } { 2 }$, then\\
(A) $f ( x )$ is an increasing function on the real line\\
(B) $f ( x )$ is a decreasing function on the real line\\
(C) $f ( x )$ is increasing on $- \infty < x \leq 0$ and decreasing on $0 \leq x < \infty$\\
(D) $f ( x )$ is decreasing on $- \infty < x \leq 0$ and increasing on $0 \leq x < \infty$