Find the Specified Quantity $y = - 5 \cos \left( 3 x + \frac { \pi } { 2 } \right)$

Multiple Choice

Find the specified quantity.
-Find the period of $y = - 5 \cos \left( 3 x + \frac { \pi } { 2 } \right)$

A) 5
B) $\frac { \pi } { 2 }$
C) $\frac { 2 \pi } { 3 }$
D) $\pi$