Compare the diversity of india with that of europe

Europe is more diverse than India in terms of ethnic groups because it's composed of a large variety of countries and has higher international migration than India. Because of the number of different countries, they also have a significant amount of different languages.

Sources:

India demographics: https://www.cia.gov/library/publications/the-world-factbook/geos/in.html

Europe demographics: https://www.cia.gov/library/publications/the-world-factbook/geos/ee.html

i would say your answer is a)

sorry if im wrong

newly independent countries of the former ussr