已知 $I_1=\int_0^1 \frac{x}{2(1+\cos x)} \mathrm{d} x, I_2=\int_0^1 \frac{\ln (1+x)}{1+\cos x} \mathrm{~d} x, I_3=\int_0^1 \frac{2 x}{1+\sin x} \mathrm{~d} x$ ，则（
$\text{A.}$ $I_1 < I_2 < I_3$ ．
$\text{B.}$ $I_2 < I_1 < I_3$.
$\text{C.}$ $I_1 < I_3 < I_2$ ．
$\text{D.}$ $I_2 < I_3 < I_1$ ．
$\text{E.}$
$\text{F.}$