Express the Product as a Sum or Difference $\sin 7 x \cos 4 x$

Multiple Choice

Express the product as a sum or difference.
- $\sin 7 x \cos 4 x$

A) $\frac { 1 } { 2 } ( \sin 11 x + \sin 3 x )$
B) $\sin \left( \cos 28 x ^ { 2 } \right)$
C) $\frac { 1 } { 2 } ( \cos 11 x - \cos 3 x )$
D) $\frac { 1 } { 2 } ( \sin 11 x + \cos 3 x )$