Write the Given Expression as the Cosine of an Angle $\cos 30 ^ { \circ } \cos 50 ^ { \circ } + \sin 30 ^ { \circ } \sin 50 ^ { \circ }$

Multiple Choice

Write the given expression as the cosine of an angle. $\cos 30 ^ { \circ } \cos 50 ^ { \circ } + \sin 30 ^ { \circ } \sin 50 ^ { \circ }$

A) $\cos \left( 50 ^ { \circ } \right)$
B) $\cos \left( - 20 ^ { \circ } \right)$
C) $\cos \left( 80 ^ { \circ } \right)$
D) $\cos \left( 30 ^ { \circ } \right)$
E) $\cos \left( - 100 ^ { \circ } \right)$