Find the Indicated Product $\left( x ^ { k } - 8 \right) \left( x ^ { k } + 8 \right)$

Multiple Choice

Find the indicated product. Assume the variable that appears as exponent represents positive integer. $\left( x ^ { k } - 8 \right) \left( x ^ { k } + 8 \right)$

A) $x ^ { k ^ { 2 } } - 64$
B) $x ^ { 2 k } - 64$
C) $x ^ { 2 k } + 64$
D) $x ^ { 2 ^ { k } } - 64$
E) $x ^ { k ^ { 2 } } + 64$