What term was used for the state of Arunachal Pradesh during the period of the Indo-China War of 1962?

North Eastern Frontier Agency (NEFA)

The correct answer is Option 2 - North Eastern Frontier Agency (NEFA)

China claimed two areas within the Indian territory: Aksai-chin area in the Ladakh region of Jammu and Kashmir and much of the state of Arunachal Pradesh in what was then called NEFA (North Eastern Frontier Agency).
China launched a swift and massive invasion in October 1962 on both the disputed regions. The first attack lasted one week and Chinese forces captured some key areas in Arunachal Pradesh. The second wave of attack came next month. While the Indian forces could block the Chinese advances on the western front in Ladakh, in the east the Chinese managed to advance nearly to the entry point of Assam plains. Finally, China declared a unilateral ceasefire and its troops withdrew to where they were before the invasion began.