Respuesta :

Rational Numbers are the numbers which doesn't repeat, with perfect squares( specially for this case)

Among the options, only 4 is the perfect square here. As √4 = 2

In short, Your Answer would be: Option C) √4

Hope this helps!
A rational number is any number that can be expressed as the fraction of two integers.  

Square root of 4 is a rational number.

An irrational number has an infinite decimal expansion that does not repeat. Numbers that have infinite decimal expansions that do not repeat 
cannot be expressed as the fraction of two integers.