The correct answer is option 4 - occupational division of labour. The caste system in India was designed to divide society into different occupational groups or castes. Each caste had its own specific occupation or trade, and individuals were expected to work within their assigned caste. The idea was to create a society where each caste performed a different function and contributed to the overall functioning of the society. This system allowed for a smooth division of labor, with each caste specializing in a particular occupation. It was believed that this division of labor would lead to a more efficient and productive society. However, it is important to note that the caste system also led to social inequality, with individuals being born into a particular caste and facing limited opportunities for social mobility.