2. $x \in[0, \pi], y=\sin (\cos x)$ minimum value is $a$, $y=\cos (\sin x)$ minimum value is $b, y=\tan(\sin x)$ minimum value is $c$, $y=\cot(\cos x)$ minimum value is $d$. Then the relationship of $a, b, c, d$ is ( ).
(A) $d<a<c<b$
(B) $c<a<b<d$
(C) $a<d<c<b$
(D) $b<a<d<c$
2. C.

Since $a=\sin (-1)<0, b=\cos 1, c=0, d=\operatorname{ctg}(-1)<0$, we know that $b$ is the largest, $c=0$ is the second, and note that $a<d$.