In what two ways were Indians grouped into castes

There are two bases of the Indian social division into castes. The castes system has been consolidated and fed by religious practices. Ancient Hindu texts speak about four castes  or profession: brahmins (priests), warriors, merchants and workers. Brahmins were at the top of society, the elite. The other source is simply social practice. There are still several groups that are seen as inferior , the "untouchables" just like the dalits; they perform the lowest and dirtiest jobs.    Though castes don´t exist formally in Indian law, they exist in reality and social and racial divisions run still deep in India.

Explanation:

it would be that mali has the worst literacy rate than the others