The most accurate assessment of how the British used divide and rule policies in Sri Lanka is: They chose Sinhalese over Tamils in bureaucratic positions.
During British colonial rule, the British favored the Tamil minority in educational and administrative opportunities, which created divisions between the Sinhalese and Tamils and fostered resentment that later contributed to ethnic tensions in Sri Lanka. The British strategically used these divisions to maintain control over the island by leveraging ethnic differences.