Answer:
The correct answer is rational.
Explanation:
The diameter of the tree belongs to the subset of rational numbers.
Natural numbers are the numbers 1, 2, 3 4, etc. Since 18.5 has a fractional/decimal component, it is not considered a natural number. Whole numbers include all of the natural numbers, as well as 0; therefore, 18.5 is not a whole number either.
Integers include all whole numbers as well as negative numbers, but the integer category still does not encompass numbers with a decimal component. For this reason, 18.5 is not an integer either.
Therefore, the only subset of numbers that 18.5 can fall under is rational numbers. A rational number is a number that can be represented as a fraction. 18.5 can be represented as 37/2 and is thus a rational number.
You can also refer to the infographic given in the question for further clarity on which subsets of numbers are more inclusive than others.
Hope this helps!