Answer:
1, 2, 3, 5
Explanation:
only the 4th and 6th answers are not rational.
4th because it contains pi (3.1415...) and it is not eliminated, which is per definition an irrational number.
the 6th because it is (out at least contains) a square root of an not ideal squared number. there is no integer number multiplied by itself that would deliver 5.
so, this is an infinite number without any repeating pattern no matter how far we look. therefore : irrational.