Use Rational Exponents to Simplify the Following $\sqrt [ 21 ] { \mathrm { y } ^ { 14 } \mathrm { z } ^{18} }$

Multiple Choice

Use rational exponents to simplify the following.
- $\sqrt [ 21 ] { \mathrm { y } ^ { 14 } \mathrm { z } ^{18} }$

A) $y ^ { 2 / 3 } z ^{7 / 6}$
B) $y ^ { 2 / 3 } z ^ { 6 / 7 }$
C) $y ^ { 3 / 2 } z ^ { 7 / 6 }$
D) $y ^ { 3 / 2 } z ^ { 6 / 7 }$