Let $g(x)=\int_{0}^{e^{x}} \frac{f^{\prime}(t)}{1+t^{2}} d t .$ Which of the following is true?
(a) $g^{\prime}(x)$ is positive on $(-\infty, 0)$ and negative on $(0, \infty)$
(b) $g^{\prime}(x)$ is negative on $(-\infty, 0)$ and positive on $(0, \infty)$
(c) $g^{\prime}(x)$ change sign on both $(-\infty, 0)$ and $(0, \infty)$
(d) $g^{\prime}(x)$ does not change sign on $(-\infty, \infty)$