1. If $A, B$ are two interior angles of an acute $\triangle A B C$, then the complex number
$$
z=(\cos B-\sin A)+\mathrm{i}(\sin B-\cos A)
$$

in the complex plane corresponds to a point located in
(A) the first quadrant;
(B) the second quadrant;
(C) the third quadrant;
(D) the fourth quadrant.
1. (B)

Since $A+B>\frac{\pi}{2}$, it follows that $0<\frac{\pi}{2}-A<B<\frac{\pi}{2}$, thus 
$$
\begin{array}{l}
\sin \left(\frac{\pi}{2}-A\right)=\cos A, \\
\cos B-\sin A<0 .
\end{array}
$$

This indicates that $z$ is in the second quadrant.