Final answer:
Tribal groups in North East and Central India include the Adivasis and Gonds, as well as the Bodos and Khasis. The Vedic Brahmans maintained the Hindu caste system, with Brahmans at the top.
Step-by-step explanation:
The tribal groups that reside in North East and Central India include a variety of ethnic groups. The correct answer to the question is a) Adivasis and Gonds, which are prominent tribes in Central India, and b) Bodos and Khasis, predominantly found in the North East region. The Bhils and Santhals are also significant tribal communities in India. In regards to the caste system, it was the Vedic Brahmans, who maintained the system, with the Brahmans being at the top tier. Comparatively, the Gujjars and Meenas are other communities found in parts of North India but are not predominantly from these regions.