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 the interval $- \infty < x \leq 0$ and decreasing on the interval $0 \leq x < \infty$\\
(d) $f ( x )$ is decreasing on the interval $- \infty < x \leq 0$ and increasing on the interval $0 \leq x < \infty$.