Explanation:

Population density is Delhi>Bihar>West Bengal.Delhi should be the first and most of you will know this. Even if you didn’t, it’s not hard to figure out that Delhi being quite small in area compared to states, and having a large population (with all those migration) will surely have the highest population density. Now, before 2011 census, WB was the state that had the second highest population density. This changed after the census 2011 report and Bihar overtook WB. This was a thing which was quite discussed when the reports came.