A rational number is a number that can be expressed as a fraction \(\frac{p}{q}\), where \(p\) and \(q\) are integers and \(q \neq 0\).
Now, let's evaluate the options:
A. Square root of 97: \(\sqrt{97}\) is not a rational number because 97 is not a perfect square.
B. Square root of 14: \(\sqrt{14}\) is not a rational number because 14 is not a perfect square.
C. Square root of 18: \(\sqrt{18}\) can be simplified to \(3\sqrt{2}\), which is also not a rational number because \(\sqrt{2}\) is irrational.
D. Square root of 36: \(\sqrt{36} = 6\), which is a rational number because it can be expressed as \(\frac{6}{1}\).
Thus, the correct answer is D. square root of 36.