Correct answer: A. Revolutionary organisation
Explanation: The direct answer is A, revolutionary organisation. The Hindustan Socialist Republican Association, commonly called HSRA, was formed by Indian revolutionaries who wanted to end colonial rule. It supported revolutionary action and also expressed a vision of a socialist republic. Bhagat Singh and several other young revolutionaries are strongly associated with it. Option A is correct because HSRA was a revolutionary political organisation, not an ordinary social or economic body. Option B, environmental organisation, would work mainly for forests, pollution or nature; that was not HSRA's purpose. Option C, peasant cooperative, would be a member-owned economic group helping farmers, which HSRA was not. Option D, princely council, would be an institution connected with rulers or princely states; HSRA opposed colonial domination rather than serving as such a council. The word “Republican” refers to a political vision, while “Socialist” indicates an egalitarian social and economic aim; together with its revolutionary methods, this identifies the organisation. Memory cue: Bhagat Singh plus armed anti-colonial revolution points to HSRA.