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

Multiple Choice

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

A) - |cos x|
B) |cos x|
C) |cos 4x|
D) - |cos 4x|
E) - |cos 8x|