Which set of numbers is defined as natural numbers?

The set of natural numbers is typically defined as the set of positive integers starting from 1 and continuing indefinitely, which includes 1, 2, 3, 4, and so forth. Therefore, the set that contains just positive whole numbers, like the one represented in option C, accurately reflects the definition of natural numbers.

This distinction is significant because, in mathematics, natural numbers are often used to count objects and represent quantities. While some definitions might include 0 in the set of natural numbers, in the context of this question, the most commonly accepted definition excludes it, thereby aligning with the representation in option C.

Other provided options include negative numbers or zero, which do not fit into the traditional definition of natural numbers. Options that include zero or any negative values are not classified as natural numbers. Thus, the set that rightly corresponds to natural numbers is the one that lists only the positive integers.