Multiply and Simplify, If Possible $( \sqrt { 5 m } + \sqrt { 2 n } ) ( \sqrt { 5 m } - \sqrt { 2 n } )$

Multiple Choice

Multiply and simplify, if possible. All variables represent positive real numbers. $( \sqrt { 5 m } + \sqrt { 2 n } ) ( \sqrt { 5 m } - \sqrt { 2 n } )$

A) $5 m - 2 n$
B) $5 n - 2 m$
C) $- 5 m - 2 n$
D) $5 m + 2 n$
E) $- 5 m + 2 n$