The question pertains to the racial classification of the tribal population in the Andaman and Nicobar Islands and the correct answer is Negroid race.

Dissecting each provided option:

1. Australoid Race: This mostly denotes indigenous Australians and neighboring groups. The Andaman and Nicobar tribes do not fall in this category.

2. Caucasoid Race: This traditionally referred to people from the Caucusus area and was later expanded to include certain groups from Europe, North Africa, the Horn of Africa and parts of Asia. The tribal population in these islands does not fit this classification.

3. Mongoloid Race: This term is used to designate populations in East Asia, Southeast Asia, the Arctic, the Americas, and the Pacific. The inhabitants of the Andaman and Nicobar Islands do not belong here either.

4. Negroid Race: Often used to describe Sub-Saharan Africans. Despite the distance from Africa, the tribes on the Andaman and Nicobar Islands are believed to be of African origin, hence belong to the Negroid race category. Their physical features such as dark skin, peppercorn hair etc. corroborate this classification.

So, option 4 is the correct answer.