Which of the following includes the number zero?

Whole numbers include the number zero, which is a defining characteristic of this set. Whole numbers are defined as all non-negative integers, starting from zero and extending to positive integers (0, 1, 2, 3, ...). This set encompasses numbers that are used for counting and ordering but does not include any negative numbers or fractions.

In contrast, natural numbers are commonly defined as the set of positive integers starting from 1, thus excluding zero. Prime numbers are defined as natural numbers greater than 1 that have no positive divisors other than 1 and themselves, which again means they cannot include zero. Composite numbers are natural numbers greater than 1 that have additional divisors, but like prime numbers, they begin counting from 2 and do not include zero.

Thus, the correct answer, whole numbers, clearly includes zero as part of its broader definition.