Hi!
An irrational number is a number that cannot be written as a ratio or a fraction.
Let's go through each answer.
= 0.18973666...
This is irrational, because it repeats forever.
This is rational, because 2525 repeats in a pattern.
= 1
This is rational. (1/1)
This is rational (10/1)
The answer is A. √0.036.
Hope this helps! :)
-Peredhel