The set of numbers that is always rational is integers.
Integers are whole numbers that can be positive, negative, or zero, and they can always be expressed as a fraction (for example, \(3\) can be expressed as \(\frac{3}{1}\)).
While real numbers encompass both rational and irrational numbers, decimals can also be rational or irrational (e.g., \(0.5\) is rational, while \(\pi\) is irrational). Positive numbers can also be rational or irrational (e.g., \(1\) is rational, while \(\sqrt{2}\) is irrational).
So the correct response is integers.