​Determine the Period and Amplitude of the Following Function​ $$y = 3 \cos \left( \frac { 2 x } { 3 } - \frac { 1 } { 6 } \right)$$

Multiple Choice

​Determine the period and amplitude of the following function​ $$y = 3 \cos \left( \frac { 2 x } { 3 } - \frac { 1 } { 6 } \right)$$ ​

A) ​Period: 10 $\pi$ ;Amplitude: 6
B) ​Period: $\frac { \pi } { 5 }$ ;Amplitude: 3
C) ​Period: 8 $\pi$ ;Amplitude: 4
D) ​Period: $\pi$ ;Amplitude: 3
E) ​Period: 5 $\pi$ ;Amplitude: 2