The answer is:
C. The mass migration of Muslims and Hindus
The partition created two new nations, but the implementation was hasty and confusing. In some places, the new borders divided communities where Hindus, Muslims, and Sikhs resided side-by-side. The partition led to mass migrations, in which a large number of Muslims in India moved to Pakistan and Hindus from Pakistan moved to India. This shift in the population unsettled the people and sparked increased tensions.