Multiply and Then, If Possible, Simplify by Factoring $\sqrt{7 x} \sqrt{2401 y}$

Multiple Choice

Multiply and then, if possible, simplify by factoring.
- $\sqrt{7 x} \sqrt{2401 y}$

A) $49 x y$
B) $\sqrt{2401 x y}$
C) $2401 \sqrt{x y}$
D) $49 \sqrt{7 \mathrm{xy}}$