Find the Length of the Third Side of the Right $\sqrt{7} \approx 2.646$

Multiple Choice

Find the length of the third side of the right triangle. Where appropriate, give both an exact answer and an approximation to three decimal places.
-

A) $\sqrt{7} \approx 2.646$
B) 245
C) $\sqrt{637} \approx 25.239$
D) $\sqrt{245} \approx 15.652$