The correct options are
B Indian census held in 2011 was the 15th Census.
C The first census was held in India in 1872.
Census in India happens in every ten years. 15th Census happened in 2011. Uttar Pradesh comes out to have the highest population among all the states. Uttar Pradesh, with a population of 199 million people, is India's most populous state. It has about 16% of India's total population. Sikkim is the least populous state. The first census was held in India in 1872.