$\mathrm{A} C D$ Has a Diameter Of $12.0 \mathrm{~cm}$ If The D

Multiple Choice

$\mathrm{A} C D$ has a diameter of $12.0 \mathrm{~cm}$ . If the $\mathrm{CD}$ is rotating at a constant angular speed of 20.0 radians per second, then the period of the rotational motion is

A) $0.421 \mathrm{~s}$ .
B) $0.143 \mathrm{~s}$ .
C) $0.224 \mathrm{~s}$ .
D) $0.314 \mathrm{~s}$ .
E) $0.558 \mathrm{~s}$ .