1. Set $M=\left\{x \left\lvert\, x=\frac{k \pi}{2}+\frac{\pi}{4}\right., k \in \mathbf{Z}\right\}, P=\left\{x \left\lvert\, x=\frac{k \pi}{4}+\frac{\pi}{2}\right., k \in \mathbf{Z}\right\}$, then ( ).
A. $M=P$
B. $M \supset P$
C. $M \subset P$
D. $M \cap P=\varnothing$
1. C. $x=\frac{k \pi}{2}+\frac{\pi}{4}=\frac{2 k+1}{4} \pi$, and $x=\frac{k \pi}{4}+\frac{\pi}{2}=\frac{k+2}{4} \pi$.