Which of the following is 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. In this case, 7 is a prime number because it can only be divided evenly by 1 and 7, giving it exactly two distinct factors.

The other numbers listed do not meet the criteria for prime numbers. For example, 4 can be divided evenly by 1, 2, and 4, so it has more than two factors. Likewise, 6 can be divided by 1, 2, 3, and 6, showing it also has more than two factors. Finally, 8 can be divided by 1, 2, 4, and 8, which confirms it is not a prime number either. Thus, 7 stands out as a prime number among the options given.