A natural number can be defined as which of the following?

A natural number is typically defined as any positive integer. This includes numbers such as 1, 2, 3, and so on. The focus is on counting numbers that are used in everyday life for counting and ordering.

While some definitions of natural numbers may include zero, the most common definition in basic mathematics restricts natural numbers to the set of positive integers only. This is likely why the first choice is considered correct in the context of the question.

The other options do not accurately reflect the definition of natural numbers. For example, integers include negative numbers and zero, which are not part of the positive integers. Rational numbers encompass a broader range of values, including fractions, which again diverges from the strict definition of natural numbers. Lastly, all negative numbers do not fall within the category of natural numbers, as these are specifically defined as positive integers.