Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
Express the product as a sum containing only sines or cosines.
- $- 2 \sin ( 5 \theta ) \sin \theta$

A) $\cos ( 7 \theta ) - \cos ( 3 \theta )$
B) $\cos ( 6 \theta ) + \cos ( 4 \theta )$
C) $\cos ( 7 \theta ) + \cos ( 3 \theta )$
D) $\cos ( 6 \theta ) - \cos ( 4 \theta )$