Simplify the Expression $\frac { 1 } { x ^ { - 7 } }$

Multiple Choice

Simplify the expression. $\frac { 1 } { x ^ { - 7 } }$ Write the answer without using negative exponents.Assume that the variable is restricted to those numbers for which the expression is defined.

A) $x ^ { 7 }$
B) $\frac { 1 } { x ^ { 8 } }$
C) $x ^ { 8 }$
D) $\frac { 1 } { x ^ { 7 } }$