If $S$ be the area of the region enclosed by $y=e^{-x^{2}}, y=0, x=0$ and $x=1$. Then,
[More than One Option Correct 2012]
(a) $S \geq \frac{1}{e}$
(b) $S \geq 1-\frac{1}{e}$
(c) $S \leq \frac{1}{4}\left(1+\frac{1}{\sqrt{e}}\right)$
(d) $S \leq \frac{1}{\sqrt{2}}+\frac{1}{\sqrt{e}}\left(1-\frac{1}{\sqrt{2}}\right)$