A sentence has been given with a blank to be filled with an appropriate word/words. Choose the correct alternative: One must respect ______ elders without any complaints.

Correct option is B

The correct answer is (b) one’s. In formal and generalized statements, the pronoun “one” is used to refer to people in general, and the possessive form of “one” is “one’s.” Hence, to show possession (elders belonging to one), “one’s elders” is the grammatically correct and stylistically appropriate choice.
Correct sentence: “One must respect one’s elders without any complaints.”
This maintains both grammatical consistency and the formal tone of the statement.