Detailed Solution:
The correct answer is “Ainu – China”.
1) The Ainu are an indigenous people who live in Japan and Russia
2) Bushmen tribe are found in the Kalahari desert of Africa in the countries including Namibia, Zambia, Angola, Zimbabwe, Botswana, South Africa, and Lesotho.
3) The Maasai are a semi-nomadic tribe of people who live in Kenya and Tanzania.
4) Papuans are found in Papua New Guinea, an independent country in the eastern part of the world's second largest island, New Guinea.