The correct option is B Occupation
The caste system was based on the occupation of the individual. The Upper-class Muslims were high ranking officials: khans, sheikhs, etc. who were leaders of a house and owned iqtas or land.
The Middle-class Muslims were soldiers, traders, peasants and scholars.
The Lower class Muslims were labourers like carpenters, goldsmiths, cobblers, etc
In Hindus it consisted of Brahmins at the top who practised priesthood and teaching. Then came the warrior caste or Kshatriyas who indulged in warfare. But these two castes had to deviate from their traditional occupations because of communal oppression by other religions.