By definition, we have:
In mathematics, a natural number is any of the numbers that are used to count the elements of certain sets, as well as in elementary calculation operations. They are those natural numbers that serve to count elements so they are whole.
For example:
1,2,3,4,5,6,7,8,9 ... ∞
By conventional definition it will be said that any member of the next set, ℕ = {1, 2, 3, 4, ...}, is a natural number.
Integers, whole numbers, real numbers, include natural numbers.
Answer:
Natural numbers are part of every other category of number except:
B. irrational numbers.