Correct answer: A. Preparing the draft Constitution
Explanation: The direct answer is A: preparing the draft Constitution. The Constituent Assembly created a Drafting Committee to convert decisions and principles into a clear legal document. Dr B. R. Ambedkar was its chairman. Step by step: the Assembly discussed the structure and ideals of independent India; different committees made reports and recommendations; the Drafting Committee organised these materials into constitutional articles; the Assembly debated and adopted the final Constitution. Option A is correct because drafting means preparing the written form of the Constitution. Option B, building railways, is an infrastructure task, not a constitutional task. Option C, making a Salt Law, is unrelated to the committee's work. Option D, fighting the Battle of Plassey, refers to an eighteenth-century historical event and could not be the work of a constitutional committee. Memory cue: Drafting Committee = written constitutional draft = Ambedkar.