The correct answer is: a) 1
The Rajya Sabha (upper house of Indian Parliament) has 245 seats, of which 12 are nominated by the President of India and 233 are elected by the elected members of the Legislative Assemblies of the states and the Union Territories. The number of seats allotted to each state is based on its population. Arunachal Pradesh has a population of 1,381,002 (as of 2011 census), which is less than the population of 1,391,736 of Mizoram, which has 2 seats in the Rajya Sabha. Therefore, Arunachal Pradesh has only 1 seat in the Rajya Sabha.
Option b) is incorrect because Arunachal Pradesh has only 1 seat in the Rajya Sabha, not 2.
Option c) is incorrect because Arunachal Pradesh has only 1 seat in the Rajya Sabha, not 5.
Option d) is incorrect because Arunachal Pradesh does have Rajya Sabha representation, with 1 seat.