Multiply, and Then Simplify If Possible $( \sqrt { 7 } + 5 ) ( \sqrt { 7 } - 5 )$

Multiple Choice

Multiply, and then simplify if possible. Assume all variables represent positive real numbers.
- $( \sqrt { 7 } + 5 ) ( \sqrt { 7 } - 5 )$

A) $- 18$
B) 2
C) $7 - 2 \sqrt { 5 }$
D) 32