The primary constitutional document governing Arunachal Pradesh is the:

Constitution of Arunachal Pradesh
Constitution of India
North-Eastern Areas (Reorganisation) Act
Inner Line Permit Regulations

The correct answer is: b) Constitution of India.

The Constitution of India is the supreme law of India. It was adopted on 26 November 1949, and came into effect on 26 January 1950. The Constitution provides for a parliamentary system of government, with a President as the head of state and a Prime Minister as the head of government. The Constitution also guarantees certain fundamental rights to all citizens of India, including the right to equality, the right to freedom, the right against exploitation, the right to freedom of religion, cultural and educational rights, and the right to constitutional remedies.

The Constitution of India is the supreme law of Arunachal Pradesh, as it is of all other states in India. The Constitution of Arunachal Pradesh is a part of the Constitution of India, and it cannot override any provision of the Constitution of India.

The North-Eastern Areas (Reorganisation) Act, 1971, is an Act of the Parliament of India that reorganized the northeastern states of India. The Act came into effect on 21 January 1972. The Act created the states of Arunachal Pradesh, Nagaland, Manipur, Meghalaya, and Mizoram. The Act also amended the Constitution of India to provide for special provisions for the northeastern states.

The Inner Line Permit Regulations are regulations that regulate the entry of outsiders into certain areas of Arunachal Pradesh. The regulations were first issued in 1939, and they have been amended several times since then. The regulations are intended to protect the culture and traditions of the people of Arunachal Pradesh.