Use the Sum-To-Product Formulas to Rewrite the Sum or Difference $$\cos 12 \theta + \cos 8 \theta$$

Multiple Choice

Use the sum-to-product formulas to rewrite the sum or difference as a product.​ $$\cos 12 \theta + \cos 8 \theta$$ ​

A) ​ $2 \sin 10 \theta \cos 2 \theta$
B) ​ $2 \cos 10 \theta \sin 2 \theta$
C) ​ $2 \sin 12 \theta \cos 8 \theta$
D) ​ $2 \cos 10 \theta \cos 2 \theta$
E) ​ $2 \sin 10 \theta \sin 2 \theta$