To distinguish cultures,most researchers consider this to be the key identifier of group boundaries.

A) Laws
B) Material culture
C) Language
D) Taboos

Language is considered the key identifier of group boundaries as it is unique to each culture and reflects the values, beliefs, and customs of a group. It allows members of a culture to communicate and understand one another and serves as a marker of identity and belonging. While laws, material culture, and taboos are important aspects of a culture, they may vary within a single culture or be shared across different cultures, making language the most reliable identifier.