The correct option is (a) \(\frac{\sqrt{3}}{3}\)
Explanation: When the denominator of an expression contains a term with a square root, the process of converting it to an equivalent expression whose denominator is a rational number is called rationalising the denominator.
By multiplying \(\frac{1}{\sqrt{3}}\) by \(\frac{\sqrt{3}}{\sqrt{3}}\), we will get same expression since \(\frac{\sqrt{3}}{\sqrt{3}}\) = 1.
Therefore, \(\frac{1}{\sqrt{3}} = \frac{1}{\sqrt{3}} * (\frac{\sqrt{3}}{\sqrt{3}}) = \frac{\sqrt{3}}{3}\).