Final answer:
The number 5 is a prime number because it is only divisible by 1 and 5, with no other factors. So the correct answer for the question from the provided options is option B.
Step-by-step explanation:
A prime number is a number that is only divisible by 1 and itself. In the given options, the number 5 is a prime number because it is only divisible by 1 and 5, with no other factors. The numbers 1 and 2 are not prime numbers because 1 is not divisible by only 1 and itself, and 2 is divisible by 1, 2, and itself.