The correct answer is B. 1991.
The process of economic liberalization in India was initiated in 1991 by the then Prime Minister P. V. Narasimha Rao. The reforms were aimed at opening up the Indian economy to foreign investment and trade, and at reducing the role of the government in the economy. The reforms were successful in promoting economic growth and development in India.
Option A is incorrect because the process of economic liberalization in India did not start in 1951. The Indian economy was largely closed to foreign investment and trade in the 1950s and 1960s.
Option C is incorrect because the process of economic liberalization in India did not start in 1976. The Indian economy was still largely closed to foreign investment and trade in the 1970s.
Option D is incorrect because the process of economic liberalization in India did not start in 1997. The reforms were initiated in 1991, and they had already had a significant impact on the Indian economy by 1997.