Which Article of the Constitution of India provides for the power to the President to convene a joint sitting of the both the Houses of Parliament?

The correct answer is Article 108. When the two Houses disagree on an ordinary bill, because one House rejects it, the Houses disagree on amendments, or more than six months pass without the other House passing it, the President can summon a joint sitting to resolve the deadlock. The Speaker of the Lok Sabha presides, and the bill is passed by a majority of the members of both Houses present and voting, which gives the larger Lok Sabha the advantage. Joint sittings have been held only three times: in 1961, 1978 and 2002.

The other options are real Articles with different content. Article 85 deals with the summoning, prorogation and dissolution of the Houses. Article 105 covers the powers, privileges and immunities of the Houses and their members. Article 331 allowed the President to nominate Anglo-Indian members to the Lok Sabha, a provision that has now lapsed. Remember that a joint sitting cannot be used for a money bill or a constitutional amendment bill.