The correct answer is: b) 1.3 million.
Arunachal Pradesh is a state in northeastern India. It is the largest state in India by area, but has the least population. The population of Arunachal Pradesh was 1,381,000 according to the 2011 census. The population density of Arunachal Pradesh is 13 people per square kilometer. The majority of the population of Arunachal Pradesh is tribal. The main languages spoken in Arunachal Pradesh are Hindi, Assamese, and English. The capital of Arunachal Pradesh is Itanagar.
Option a) 500,000 is incorrect because the population of Arunachal Pradesh was 1,381,000 according to the 2011 census.
Option c) 5 million is incorrect because the population of Arunachal Pradesh was 1,381,000 according to the 2011 census.
Option d) 10 million is incorrect because the population of Arunachal Pradesh was 1,381,000 according to the 2011 census.