Find the Exact Solutions of the Given Equation in the Interval

Multiple Choice

Find the exact solutions of the given equation in the interval [0,2π) .​ $$\cos 2 x + 3 \cos x + 2 = 0$$

A) ​ $x = 0 , \pi , \frac { 2 \pi } { 3 } , \frac { 5 \pi } { 3 }$
B) ​ $x = \pi , \frac { \pi } { 3 } , \frac { 5 \pi } { 3 }$
C) ​ $x = \pi , \frac { 2 \pi } { 3 } , \frac { 4 \pi } { 3 }$
D) ​x = 0
E) ​ $x = 0 , \pi , \frac { \pi } { 3 } , \frac { 4 \pi } { 3 }$