已知全集为$R$，集合$A=\left\{\overline{)x}{\left(\frac{1}{2}\right)}^x⩽1\right\},B=\left\{\overline{)x}{x}^2-6x+8⩽0\right\}$，则$A\cap C_{R}B=$（）

A．

$\left\{\overline{)x}x⩽0\right\}$

B．

$\left\{\overline{)x}2⩽x⩽4\right\}$

C．

$\left\{\overline{)x}0⩽x<2或x>4\right\}$

D．

$\left\{\overline{)x}0<x⩽2或x⩾4\right\}$