在极坐标系中，圆 $\rho =2\cos \theta$的垂直于极轴的两条切线方程分别为（  ）

A．	$\theta =0(\rho \in R)和\rho \cos \theta =2$	B．	$\theta =\frac{\pi }{2}(\rho \in R)和\rho \cos \theta =2$
C．	$\theta =\frac{\pi }{2}(\rho \in R)和\rho \cos \theta =1$	D．	$\theta =0(\rho \in R)和\rho \cos \theta =1$