Determine the Amplitude or Period as Requested $y = - 4 \cos ( 6 \pi x + 3 \pi )$

Multiple Choice

Determine the amplitude or period as requested.
Graph Variations of y = cos x
-Period of $y = - 4 \cos ( 6 \pi x + 3 \pi )$

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