In which one of the following union territories, do the people of the Onge tribe live?

The Onge (Onges) are explicitly listed among the surviving indigenous tribes of the Andaman and Nicobar Islands, confirming their presence in that Union Territory [1]. More specifically, official local sources state that the Onges inhabit Little Andaman Island (with settlements at places such as Dugong Creek and South Bay), identifying them as a distinct hunting-and-gathering tribe native to Little Andaman within the Andaman and Nicobar Islands [2]. Therefore the correct Union Territory where the Onge people live is the Andaman and Nicobar Islands.

Sources

1. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 2: Physiography > Islands of the Bay of Bengal > p. 68
2. [2] https://southandaman.nic.in/people_culture/