Correct Answer: (c) 26 October, 1947
Solution:On 26 October, 1947, the Maharaja of Kashmir, Hari Singh, handed over the 'Instrument of Accession' (IOA) to Jawaharlal Nehru. J.L. Nehru appointed Sheikh Abdullah as Prime Minister and the Indian Army entered Jammu and Kashmir on 27 October, 1947 to repel the invaders.