7. Let $a=\sin \left(\sin 2008^{\circ}\right), b=\sin \left(\cos 2008^{\circ}\right)$, $c=\cos \left(\sin 2008^{\circ}\right), d=\cos \left(\cos 2008^{\circ}\right)$. Then the size relationship of $a, b, c, d$ is ( ).
(A) $a<b<c<d$
(B) $b<a<d<c$
(C) $c<d<b<a$
(D) $d<c<a<b$
7. B.

Since $2008^{\circ}=5 \times 360^{\circ}+180^{\circ}+28^{\circ}$, therefore,
$$
\begin{array}{l}
a=\sin \left(-\sin 28^{\circ}\right)=-\sin \left(\sin 28^{\circ}\right)0, \\
d=\cos \left(-\cos 28^{\circ}\right)=\cos \left(\cos 28^{\circ}\right)>0 .
\end{array}
$$
$$
\text { Also } \sin 28^{\circ}<\cos 28^{\circ} \text {, hence } b<a<d<c \text {. }
$$