Answer: a. Race
Step-by-step explanation:
A race can be defines as the group of human beings which can be categorized on the basis of the shared physical qualities like facial forms, hair type, stature and others and on the basis of social qualities like language, occupation and others.
Race is not a culture differentiator this is because people belonging to the same race may follow different culture practices.
Rite, ritual and norm all are the examples of cultural differentiator:
Rite can be defined as a religional or cultural ceremony.
Ritual can be defined as the process in which religional ceremony is performed in an orderly manner.
Norm can be defined as rule or set of rules which are required to be followed by the members of society. A norm controls the controls, guide and regulate the behaviors of the members of the society.