The process by which a low caste or tribe or other group takes over the customs, beliefs of twice-born caste is:

Sanskritization

The correct answer is option 4: Sanskritization

The term sanskritisation was coined by M.N. Srinivas. It may be briefly defined as the process by which a ‘low’ caste or tribe or other group takes over the customs, ritual, beliefs, ideology and style of life of a high and, in particular, a ‘twice-born (dwija) caste’.