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

Multiple Choice

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

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