Castes in Indian society refer to a social group where membership is decided by birth. Members of such local groups are endogamous, i.e. they tend to enter into marital relationships among themselves. They often have related political preferences.
The answer in the space provided is experiments. It is because in order to produce causation or to likely have a cause of something in particular, they need to conduct experiments in which they will likely form new ideas and test this ideas to form something new that will cause and contribute to others and will be of gain of knowledge.
