Which of the following is a characteristic of real numbers?

Real numbers encompass a wide range of numerical types, making them a fundamental concept in mathematics. The correct answer highlights that real numbers include both irrational and rational numbers.

Rational numbers are those that can be expressed as the quotient of two integers, where the denominator is not zero. This category includes whole numbers (which are a subset of rational numbers) and integers, allowing for a diverse set of values including fractions and repeating decimals.

Irrational numbers, on the other hand, cannot be expressed as the quotient of two integers. They manifest in forms such as non-repeating and non-terminating decimal expansions, like the square root of 2 or pi.

By encompassing both categories—rational and irrational—real numbers provide a comprehensive framework for understanding quantities, measurements, and various mathematical operations. This essential inclusivity of different types of numbers under the real numbers classification supports their importance in mathematics.