#1
Irrational numbers are numbers with infinite decimals values that are not repeating (ex. Pi 3.14159265....). Whole numbers don’t have decimal values in the first place, so all whole numbers are therefore rational.
Keep in mind that just because a number has decimal values doesn’t mean it’s irrational (ex. 4.5 is a rational number). It needs to have infinite non-repeating decimal values to be irrational.