Answer:
Natural numbers
Explanation:
Rational numbers are numbers which can be expressed in the form a/b ; such that b ≠ 0 ; hence, rational numbers can be certain non-recurring decimal values.
Integer values are numbers which can be written without any fractional component. While natural numbers are characterized as being whole and non-negative
To represent population values, number of people or species cannot be fractional and cannot be negative, hence natural numbers is the best option.