​Determine the Period and Amplitude of the Following Function​ $$y = 5 \cos \left( \frac { 5 x } { 7 } + \frac { 1 } { 3 } \right)$$

Multiple Choice

​Determine the period and amplitude of the following function​ $$y = 5 \cos \left( \frac { 5 x } { 7 } + \frac { 1 } { 3 } \right)$$ ​

A) ​Period: 16 $\pi$ ;Amplitude: 10
B) ​Period: $\pi$ ;Amplitude: 5
C) ​Period: 5 $\pi$ ;Amplitude: 6
D) ​Period: $\frac { \pi } { 2 }$ ;Amplitude: 5
E) ​Period: 8 $\pi$ ;Amplitude: 4