Graph two full periods of the function \( f ( x ) = \cos ( 4 x ) \) and state the amplitude and period. Enter the exact answers.
For the number \( \pi \) , either choose \( \pi \) from the drop-down menu or type in Pi (with a capital P). Amplitude: \( A = \)
Period: \( P = \)
Select the correct graph of the function \( f ( x ) = \cos ( 4 x ) \) .