Identify the pronoun in the given sentence.
It is Atul who gave me the pen. Identify 'who' in the given sentence.
The sentence "It is Atul who gave me the pen" uses "who" to link a describing clause back to a person already named in the sentence, Atul. We need to identify exactly what part of speech "who" is playing here.
Since "who" both refers back to the noun "Atul" and introduces a clause about him, it is best classified as a relative pronoun.
Let's summarize:
So the correct answer is option (b), relative pronoun.