Solve the Problem $x , 0 \leq x \leq 2 \pi$

Multiple Choice

Solve the problem.
-For what numbers $x , 0 \leq x \leq 2 \pi$ , does $\cos x = - 1$ ?

A) $\frac { \pi } { 2 } , \frac { 3 \pi } { 2 }$
B) $\frac { \pi } { 2 }$
C) $\pi$
D) none