Which of the following defines a whole number?

A whole number is defined as a member of the set of natural numbers and zero. The set of whole numbers includes all the non-negative integers, which are zero and all the positive integers (1, 2, 3, etc.). This definition is essential in mathematics because it establishes whole numbers as the simplest and most fundamental counting numbers starting from zero, leading into positive integers without fractions or decimals.

The other choices do not accurately define whole numbers. A whole number includes zero and also all positive integers, which contradicts the idea of a number being only positive or less than one. Additionally, a whole number cannot have a decimal value, as whole numbers are strictly non-fractional. This clarity is crucial in distinguishing whole numbers from other numerical classifications.