144 The graph of the function $y=\arccos x(-1 \leqslant x \leqslant 1)$ is symmetric about the $y$-axis and is denoted as $C_{1}$. The graph of $C_{1}$ symmetric about the line $y=x$ is denoted as $C_{2}$. Then, the analytical expression of $C_{2}$ is
A. $y=\cos x(0 \leqslant x \leqslant \pi)$
B. $y=\arcsin x(-1 \leqslant x \leqslant 1)$
C. $y=-\cos x(0 \leqslant x \leqslant \pi)$
D. None of the above answers is correct
144 C. $C_{1}$ represents the function $y=\operatorname{arc} \cos (-x), C_{2}$ represents the function $x=\operatorname{arc} \cos (-y)$, i.e., $y=-\cos x$.