How many princely states joined Pakistan out of 565 at partition?

At the time of the 1947 partition; 13 princely states out of 565 in the Indian subcontinent acceded to Pakistan; including states like Bahawalpur and Swat. This number is historically verified; distinguishing it from the incorrect options of 11; 12; or 14. This question tests knowledge of Pakistan’s formation; with option C being the correct answer.