设函数$f\left(x\right)=\sin (\omega \phi +\phi )+\cos (\omega \phi +\phi )(\omega >0,|\phi |<\frac{\pi }{2})$的最小正周期为$\pi$，且$f(-x)=f\left(x\right)$，则（）

A．	$f\left(x\right)$在 $(0,\frac{\pi }{2})$单调递减
B．	$f\left(x\right)$在 $(\frac{\pi }{4},\frac{3\pi }{4})$单调递减
C．	$f\left(x\right)$在 $(0,\frac{\pi }{2})$单调递增
D．	$f\left(x\right)$在 $(\frac{\pi }{4},\frac{3\pi }{4})$单调递增