Determine the Amplitude or Period as Requested $y = \frac { 1 } { 3 } \cos 4 x$

Multiple Choice

Determine the amplitude or period as requested.
Graph Variations of y = cos x
-Amplitude of $y = \frac { 1 } { 3 } \cos 4 x$

A) $\frac { 1 } { 3 }$
B) 4
C) $\frac { \pi } { 4 }$
D) $6 \pi$