The Function Graphed Is of the Form Y = a Sin

Multiple Choice

The function graphed is of the form y = a sin bx or y = a cos bx, where b > 0. Determine the equation of the graph.
-

A) $y = 3 \cos \left( \frac { 1 } { 2 } x \right)$
B) $y = 3 \sin \left( \frac { 1 } { 2 } x \right)$
C) $y = 3 \cos ( 2 x )$
D) $y = 3 \sin ( 2 x )$