Simplify Assume That All Variables Represent Positive Real Numbers $(5-2 \sqrt{5})^{2}$

Multiple Choice

Simplify. Assume that all variables represent positive real numbers.
- $(5-2 \sqrt{5}) ^{2}$

A) $45+20 \sqrt{5}$
B) $25-4 \sqrt{5}$
C) $25+4 \sqrt{5}$
D) $45-20 \sqrt{5}$