Which of the following best defines a rational number?

A rational number is defined as any number that can be expressed as a fraction, where both the numerator and the denominator are integers and the denominator is not zero. This definition encompasses not only whole numbers but also fractions and decimals that can repeat or terminate.

By stating that rational numbers include fractions and repeating decimals, we highlight that any decimal which either terminates (like 0.5, which is equivalent to 1/2) or repeats (like 0.333..., which is equivalent to 1/3) qualifies as a rational number. This understanding is crucial for recognizing the characteristics of rational numbers in the broader category of real numbers.

On the other hand, whole numbers are a subset of rational numbers (but do not encompass all rational numbers), non-terminating decimals that do not repeat (like π) are not rational, and numbers without a fractional component include whole numbers and irrational numbers, which are not part of the rational number definition. Thus, the most accurate definition among the choices provided is that rational numbers include fractions and repeating decimals.