Which of the following is an example of whole numbers?

Whole numbers are defined as non-negative integers that do not include fractions or decimals. They start from zero and go upwards (0, 1, 2, 3, 4, ...). The number two is a perfect representation of a whole number as it is a positive integer without any decimal or fractional components.

In contrast, the other options given are either fractions or decimal representations, which disqualify them from being classified as whole numbers. For example, 1.5 is a decimal, and both 3.14 and 2.71 have values that include decimal points as well. Thus, two stands out as the only option fulfilling the criteria for whole numbers.