Answer:
Last one
Explanation:
For something to be 'irrational', you shouldn't be able to put it in a fraction. You can know if something is irrational because when you look at it in decimal form and the numbers after the decimal point are random and do not follow a pattern (ie 276276276...).
Hence that is why pi is irrational as well because the numbers after the dec. point are: 3.1415626.... there is no visible pattern