Simplify Write the Answer Using Positive Exponents Only $\left( \frac { \mathrm { a } } { 7 } \right) ^ { 3 }$

Multiple Choice

Simplify. Write the answer using positive exponents only.
- $\left( \frac { \mathrm { a } } { 7 } \right) ^ { 3 }$

A) $\frac { a ^ { 4 } } { 2401 }$
B) $\frac { a ^ { 3 } } { 343 }$
C) $\frac { a } { 7 }$
D) $\frac { a ^ { 3 } } { 7 }$