Use the Sum-To-Product Formulas to Rewrite the Sum or Difference $$\sin 9 \theta + \sin 7 \theta$$

Multiple Choice

Use the sum-to-product formulas to rewrite the sum or difference as a product.​ $$\sin 9 \theta + \sin 7 \theta$$ ​

A) ​ $2 \sin 8 \theta \sin \theta$
B) ​ $2 \cos 8 \theta \cos \theta$
C) ​ $2 \sin 8 \theta \cos \theta$ ​
D) ​ $2 \cos 8 \theta \sin \theta$
E) ​ $2 \sin 9 \theta \cos 7 \theta$