A number is prime if it...

A prime number is defined as a natural number greater than one that has exactly two distinct positive divisors: one and itself. This means that for a number to be classified as prime, it can only be divided evenly by 1 and by the number itself.

For example, the number 5 is prime because its only divisors are 1 and 5. In contrast, composite numbers, like 4, have more than two positive divisors (1, 2, and 4), which disqualifies them from being prime. The definition specifically excludes numbers less than 2, as they do not meet these criteria. Therefore, the correct answer clearly identifies that a prime number must possess only two positive divisors.