Use the Half-Angle Formula to Simplify the Given Expression $\sqrt { \frac { 1 + \cos 8 x } { 2 } }$

Multiple Choice

Use the half-angle formula to simplify the given expression.
$\sqrt { \frac { 1 + \cos 8 x } { 2 } }$

A) cos |2x|
B) cos |8x|
C) cos |16x|
D) cos |32x|
E) cos |4x|