.3 :-Which one of the following is not a prime number?31617191

The question is asking which of the following numbers is not a prime number: 3, 16, 17, 91.

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.

Let's examine each number:

1. 3: This number only has 1 and itself as divisors, so it is a prime number.
2. 16: This number has 1, 2, 4, 8, and 16 as divisors, so it is not a prime number.
3. 17: This number only has 1 and itself as divisors, so it is a prime number.
4. 91: This number has 1, 7, 13, and 91 as divisors, so it is not a prime number.

So, the numbers 16 and 91 are not prime numbers.