Which of the following defines a prime number?

A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. This means that a prime number can only be divided evenly (without a remainder) by the number 1 and the number itself. For example, the number 5 is prime because its only divisors are 1 and 5. In contrast, numbers like 4 and 6 are not prime because they can be divided evenly by numbers other than just 1 and themselves (4 can be divided by 2, and 6 can be divided by 2 and 3).

The other definitions provided do not accurately capture the essence of prime numbers. A prime number is specifically characterized by its inability to be divided by other numbers, other than 1 and itself, which is why the correct choice focuses on the absence of additional positive divisors.