The smallest positive number $K$ for which the inequality $\mid \sin ^2 x – \sin ^2 y \mid \leq K \mid x-y \mid$ holds for all $x$ and $y$ is
- $2$
- $1$
- $\frac{\pi}{2}$
- there is no smallest positive value of $K$; any $K>0$ will make the inequality hold.