Missionary activities by Christian groups were introduced in Arunachal Pradesh during the British period, leading to:

The correct answer is: d) All of the above.

Missionary activities by Christian groups were introduced in Arunachal Pradesh during the British period, leading to religious conversions, spread of education, and changes in social customs.

• Religious conversions: The missionaries converted many people to Christianity. This led to a change in the religious landscape of Arunachal Pradesh.
• Spread of education: The missionaries set up schools and hospitals in Arunachal Pradesh. This led to an increase in literacy rates and a better standard of living for many people.
• Changes in social customs: The missionaries introduced new ideas about gender equality, education, and health. This led to changes in the way people lived their lives.

The introduction of Christianity had a significant impact on the people of Arunachal Pradesh. It changed the way they lived their lives, their beliefs, and their customs.