Multiply and Then, If Possible, Simplify by Factoring $\sqrt{5 x} \sqrt{15 x}$

Multiple Choice

Multiply and then, if possible, simplify by factoring.
- $\sqrt{5 x} \sqrt{15 x}$

A) $5 x \sqrt{3}$
B) $5 \sqrt{3 x}$
C) $25 x \sqrt{3}$
D) $\sqrt{75 x^{2}}$