Perform the Indicated Operation and Write Your Answer with Positive $$\frac { m n ^ { - 1 } - n m ^ { - 1 } } { m ^ { 2 } - n ^ { 2 } }$$

Multiple Choice

Perform the indicated operation and write your answer with positive integer exponents.
- $$\frac { m n ^ { - 1 } - n m ^ { - 1 } } { m ^ { 2 } - n ^ { 2 } }$$

A) $\frac { 1 } { m n }$
B) $\frac { 1 } { m + n }$
C) $m n$
D) $m + n$