Answer:
The correct answer is a.
Step-by-step explanation:
A caste system is a form of social stratification where a certain lifestyle, rights, obligations, and societal expectations are ascribed to individuals or social groups by virtue of their lineage. Caste societies are strictly hierarchical and highly unequal: how scarce resources and social rewards in a society are distributed according to one's caste, and any other form of arrangement or distribution of resources is difficult or impossible. Social mobility in caste systems is very rare or not seen at all.