The correct answer to this open question is the following.
The purpose of Britain's “divide-and-rule” tactic in South Asia was to antagonize relations between Muslims and Hinduisms thus weakening both in their ability to oppose the colonial rule.
We are referring to the partition of India, in which India was divided into two countries: Pakistan and India. India was formed mostly by Hinduists and Pakistan had mostly Muslims. This way the British government found a way to split the nation to create both factions that were antagonists and reduce the probability to face strong opposition to the English crown.