An irreducible factor of is:
Step 1: Explanation of the correct option
An irreducible factor is a factor that cannot be expressed further as a product of factors. Such a factorization is called an irreducible factorization.
Factorization of
It is clear that cannot be expressed further as a product of factors. Hence is an irreducible factor of .
Therefore option (C) is correct.
Step 2: Explanation of the incorrect option
Option (A): can be factorized as , therefore it is not an irreducible factor of .
Option (B): can be factorized as , therefore it is not an irreducible factor of .
Option (D): can be factorized as , therefore it is not an irreducible factor of .
Therefore option (A), (B), and (D) do not give the correct answer.