The correct answer is: b) 1987.
Arunachal Pradesh is a state in northeastern India. It is the largest state in the country by area, and the 8th most populous. The capital of Arunachal Pradesh is Itanagar.
Arunachal Pradesh was a part of the North-East Frontier Agency (NEFA) until 1972. In 1972, NEFA was renamed Arunachal Pradesh, and it became a Union Territory. In 1987, Arunachal Pradesh achieved full statehood.
The following are the options for the question:
a) 1975: This is incorrect because Arunachal Pradesh was not a state in 1975. It was a Union Territory.
b) 1987: This is the correct answer because Arunachal Pradesh achieved full statehood in 1987.
c) 1992: This is incorrect because Arunachal Pradesh was already a state in 1992.
d) 2000: This is incorrect because Arunachal Pradesh was already a state in 2000.