设 $M=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \frac{(1+x)^2}{1+x^2} \mathrm{~d} x, N=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \frac{1+x}{\mathrm{e}^x} \mathrm{~d} x, K=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}(1+\sqrt{\cos x}) \mathrm{d} x$, 则
$\text{A.}$ $M>N>K$.
$\text{B.}$ $M>K>N$.
$\text{C.}$ $K>M>N$.
$\text{D.}$ $K>N>M$.
$\text{E.}$
$\text{F.}$