A rational number is defined as any number that can be expressed as the quotient or fraction \(\frac{p}{q}\) of two integers, where \(q \neq 0\).
Among the choices provided:
- The square root of 15 (\(\sqrt{15}\)) is an irrational number, as 15 is not a perfect square.
- The square root of 16 (\(\sqrt{16}\)) is 4, which is a rational number (since it can be expressed as \(\frac{4}{1}\)).
- The square root of 17 (\(\sqrt{17}\)) is an irrational number, as 17 is not a perfect square.
- The square root of 18 (\(\sqrt{18}\)) simplifies to \(3\sqrt{2}\), which is also irrational.
Therefore, the only rational number among the options is square root of 16.