Find the Length of the Third Side of the Right $c$

Multiple Choice

Find the length of the third side of the right triangle. Assume that $c$ represents the length of the hypotenuse. Give an exact answer and, if appropriate, an approximation to three decimal places.
- $\mathrm{a}=\sqrt{3}, \mathrm{c}=\sqrt{10}$

A) $b=\sqrt{7}, b \approx 2.646$
B) $b=2 \sqrt{2}, b \approx 2.828$
C) $b=7$
D) $b=2 \sqrt{7}, b \approx 5.292$