How are social classes and social castes related?

The class and caste jointly distinguish the rank of a person in a social strain. Especially in rural areas where the caste system is still maintained, it’s the fundamental basis for determining one’s economic position. Even in modern societies, this is still observed by distinguishing the upper and middle classes. They are related since they serve as a relevant system of social stratification. 

Icould be wrong but i would say b.