Rewrite as a Single Expression $\theta$ )Cos(3 $\theta$ ) - Cos(6 $\theta$ )Sin(3 $\theta$

Rewrite as a single expression. sin(6 $\theta$ ) cos(3 $\theta$ ) - cos(6 $\theta$ ) sin(3 $\theta$ )

A) cos(9 $\theta$ )
B) cos(3 $\theta$ )
C) sin(9 $\theta$ )
D) sin(3 $\theta$ )