Correct Option: A

The Arab conquest of Sindh by Muhammad Bin Qasim in 712 AD gave the Muslims a firm foothold on the sub-continent. Qasim’s conquest of Sindh and Punjab laid the foundations of Islamic rule in the Indian subcontinent. The description of Hiuen Tsang, a Chinese historian, leaves no doubt that the social and economic restrictions inherent in the caste differentiations of Hindu society had however, gradually sapped the inner vitality of the social system and Sindh fell without much resistance before the Muslim armies.