The correct answer matches the ethnic communities to their respective countries correctly:

Option 1: A-2, B-3, C-4, D-1 is correct because:

A. Apatani is an ethnic group from India (2). They are primarily found in Arunachal Pradesh.

B. Dayak refers to a large group of indigenous people in Indonesia (3), mainly in the central parts of Borneo, which is shared by Malaysia, Brunei, and Indonesia.

C. Dinka is a major ethnic group in Sudan (4). They live in the Nile Valley and are a predominantly pastoral people.

D. Uighur is a Turkic ethnic group native to China (1), primarily in the Xinjiang Uighur Autonomous Region.

Other options are incorrect because they incorrectly match the ethnic communities to the respective countries. For example, option 2 suggests Apatani are from Indonesia or Uighurs are from Sudan, which is incorrect. Similarly, options 3 and 4 offer other incorrect matches.