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 $0 \leq x < \infty$