Simplify the Radical Expression $\sqrt [ 4 ] { x ^ { 27 } }$

Multiple Choice

Simplify the radical expression. Assume that all variables represent positive real numbers.
- $\sqrt [ 4 ] { x ^ { 27 } }$

A) $x ^ { 4 } \sqrt [ 6 ] { x ^ { 3 } }$
B) $x ^ { 4 } \sqrt { 3 }$
C) $x ^ { 6 } \sqrt { 3 }$
D) $x ^ { 6 } \sqrt [ 4 ] { x ^ { 3 } }$