The correct answer is A. 21 seats.
Section 48 of the Jammu and Kashmir Constitution states that the total number of seats in the Legislative Assembly of the State shall be 100, of which 24 seats shall be reserved for the Scheduled Castes. The remaining 76 seats shall be distributed among the territorial constituencies of the State in such a manner that each constituency has approximately an equal population.
However, as per the Instrument of Accession, the State of Jammu and Kashmir has ceded to the Dominion of India only the territories that were under its control on 15 August 1947. The territories that came under the control of Pakistan on that date, including the Pakistan occupied Kashmir (PoK), are not part of the State of Jammu and Kashmir.
Therefore, the 21 Assembly seats that were allotted to the territorial constituencies of the PoK under the Jammu and Kashmir Constitution remain officially vacant.