Find the Specified Quantity $y = 5 \cos \left( 4 x + \frac { \pi } { 3 } \right)$

Multiple Choice

Find the specified quantity.
-Find the amplitude of $y = 5 \cos \left( 4 x + \frac { \pi } { 3 } \right)$ .

A) 4
B) 5
C) $\frac { \pi } { 2 }$
D) 20