Use Rational Exponents to Simplify the Following $\sqrt [ 56 ] { x ^ { 8 } }$

Multiple Choice

Use rational exponents to simplify the following.
- $\sqrt [ 56 ] { x ^ { 8 } }$

A) $x ^ { 7 }$
B) $x ^ { 1 / 8 }$
C) $x ^ { 1 / 56 }$
D) $x ^ { 1 / 7 }$