The Function Graphed Is of the Form Y $$y = a \sin b x \text { or } y = a \cos b x , \text { where } b > 0$$

Multiple Choice

The function graphed is of the form y $$y = a \sin b x \text { or } y = a \cos b x , \text { where } b > 0$$ Determine the equation of the graph.
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A) $y = 4 \cos \left( \frac { 1 } { 3 } x \right)$
B) $y = 4 \sin \left( \frac { 1 } { 3 } x \right)$
C) $y = - 4 \cos ( 3 x )$
D) $y = 4 \cos ( 3 x )$