Write with Positive Exponents $64 ^ { - 4 / 3 }$

Multiple Choice

Write with positive exponents. Simplify if possible.
- $64 ^ { - 4 / 3 }$

A) $\frac { 1 } { 256 }$
B) not a real number
C) $- \frac { 1 } { 256 }$
D) 256