Well, plug in all the values.
(sqrt)3>3
False. 3 would be more than it's square root.
(sqrt)9>3
3>3
This is false. 3 is not bigger than 3. They are equal.
(sqrt)15>3
3.8729..... >3
That is true,
(sqrt)10>3
3.1622>3
This true.
-3 and 0 would not work either.
So,
"C" and "D" are correct solutions.
I hope this helps!
~kaikers