Use Rational Exponents to Write as a Single Radical Expression $\sqrt [ 9 ] { x } \cdot \sqrt [ 3 ] { x ^ { 2 } }$

Multiple Choice

Use rational exponents to write as a single radical expression.
- $\sqrt [ 9 ] { x } \cdot \sqrt [ 3 ] { x ^ { 2 } }$

A) $x ^ { 21 }$
B) $\sqrt [ 9 ] { \mathrm { x } ^ { 7 } }$
C) $\sqrt { x ^ { 7 } }$
D) $\sqrt [ 9 ] { \mathrm { x } ^ { 3 } }$