Question

The number which is neither prime nor composite is

• A. $4$
• B. $3$
• C. $2$
• D. $1$

Answer 1

The correct option is D

$1$

Defining Prime numbers: Prime numbers are natural numbers that are divisible by '$1$' and the number itself. In other words, prime numbers are positive integers greater than $1$with exactly two factors, $1$ and the number itself.

Composite numbers: A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than '$1$' and itself.

The explanation for option(A):

$\Rightarrow 4=2\times 2$

So, $2$ is a divisor of '$4$'. So, it is a composite number.

The explanation for option(B):

$\Rightarrow 3=3\times 1$

The number '$3$‘ has no other factor other than ’$1$' and itself. So, ‘$3$’ is a prime number.

The explanation for option(C):

$\Rightarrow 2=2\times 1$

The number ‘$2$’ has no other factor other than ‘$1$’ and itself. So, '$2$' is a prime number.

The explanation for option(D):

$\Rightarrow$ The number '$1$‘ has only one factor, i.e., ’$1$', So, it is neither prime nor composite.

Therefore, option (D) is the correct answer.