Find the Zeros of the Function in the Interval $[-2 \pi, 2 \pi]$

Multiple Choice

Find the zeros of the function in the interval $[-2 \pi, 2 \pi]$ .
- $$f ( x ) = 3 \cos x$$

A) $\pm \frac { \pi } { 2 } , \pm \pi , \pm \frac { 3 \pi } { 2 } , \pm 2 \pi$
B) $0 , \pm \frac { \pi } { 2 } , \pm \frac { 3 \pi } { 2 }$
C) $\pm \frac { \pi } { 2 } , \pm \frac { 3 \pi } { 2 }$
D) $0 , \pm \pi , \pm 2 \pi$