In which year did Sri Lanka gain independence from British rule?

Correct answer: 1948

Sri Lanka, then known as Ceylon, gained independence from British rule in 1948. The country became independent on 4 February 1948 through a constitutional and political process rather than a prolonged war like some other colonies. It remained within the Commonwealth at first, but it became a republic in 1972 and adopted the name Sri Lanka. The 1948 date is an important part of Asian decolonization.

Option B, 1948, is correct. The other dates refer to different events or countries: 1960 was a major year of African decolonization, 1957 is associated with the independence of Malaya, and 1971 is associated with the independence of Bangladesh. The question asks specifically about freedom from British rule, so the relevant answer is 1948, not the later change to a republic.