Write the Expression with Only Positive Exponents and Evaluate If $- x ^ { - 4 }$

Multiple Choice

Write the expression with only positive exponents and evaluate if possible. Assume all variables represent nonzero real
numbers.
- $- x ^ { - 4 }$

A) $- 4 x$
B) $- \frac { 1 } { x ^ { 4 } }$
C) $4 \mathrm { x }$
D) $\frac { 1 } { x ^ { 4 } }$