Which one is an example of 'relative pronoun'?

That এবং which দুইটিই relative pronoun হিসেবে ব্যবহৃত হয়।
অপশনে দ্বৈত উত্তর থাকায় বাতিল করা হয়েছে।

Relative pronouns introduce relative clauses.
The most common relative pronouns are who, whom, whose, which, that.
The relative pronoun we use depends on what we are referring to and the type of relative clause.

Source: Cambridhe Dictionary