Use the Laws of Exponents to Simplify Each Expression Using $\frac { x ^ { - 4 } } { x ^ { - 11 } }$

Multiple Choice

Use the laws of exponents to simplify each expression using positive exponents only. Assume all variables represent nonzero real numbers.
- $\frac { x ^ { - 4 } } { x ^ { - 11 } }$

A) $x ^ { 15 }$
B) $\frac { 1 } { 15 }$
C) $\frac { 1 } { 7 }$
D) $x ^ { 7 }$ x x