Write the Given Expression as the Cosine of an Angle $\cos 45 ^ { \circ } \cos 40 ^ { \circ } + \sin 45 ^ { \circ } \sin 40 ^ { \circ }$

Multiple Choice

Write the given expression as the cosine of an angle.
$\cos 45 ^ { \circ } \cos 40 ^ { \circ } + \sin 45 ^ { \circ } \sin 40 ^ { \circ }$

A) $\cos \left( 45 ^ { \circ } \right)$
B) $\cos \left( 5 ^ { \circ } \right)$
C) $\cos \left( - 80 ^ { \circ } \right)$
D) $\cos \left( 40 ^ { \circ } \right)$
E) $\cos \left( 85 ^ { \circ } \right)$