What are integers?

Integers are defined as the set of whole numbers that include all positive whole numbers, negative whole numbers, and zero. This definition encompasses the entire number line without any fractional or decimal components. By selecting the option that includes whole numbers and their opposites, it correctly reflects that integers consist of 0, positive integers (1, 2, 3, ...) and negative integers (-1, -2, -3, ...).

The other choices do not accurately represent the complete set of integers. For instance, whole numbers only would exclude negative values and zero, while numbers expressed as fractions would refer to rational numbers rather than integers. Similarly, focusing exclusively on negative numbers overlooks the positive integers and zero, which are essential components of the integer set. Thus, the assertion that integers encompass whole numbers and their opposites accurately captures their full definition in mathematics.