Complete the Identity $\sin 4 x \sin 6 x \cos 4 x \cos 6 x =$

Multiple Choice

Complete the identity.
- $\sin 4 x \sin 6 x \cos 4 x \cos 6 x =$ ?

A) $\frac { \cos ^ { 2 } 2 x - \cos ^ { 2 } 10 x } { 4 }$
B) $\frac { \sin ^ { 2 } 48 x } { 4 }$
C) $\frac { \cos ^ { 2 } 10 x + \cos ^ { 2 } 2 x } { 4 }$
D) $\cos ^ { 2 } 48 x$