Which of the following best describes real numbers?

The best description of real numbers is that they encompass all numbers on the number line. This includes various types of numbers such as integers, rational numbers (like fractions), and irrational numbers (like the square root of 2 or pi). Real numbers can be positive, negative, or zero, and they represent all possible values that can exist along the continuum of the number line.

The other options are more limited in scope. For instance, integers only represent whole numbers, which excludes fractions and decimals. Rational numbers refer specifically to numbers that can be expressed as a fraction, which means they also exclude irrational numbers. Negative numbers include only those values less than zero, thus omitting positive numbers and zero. Hence, the choice that encompasses the entirety of the number line is the most accurate description of real numbers.