A brief reading of the sentences suggests that the paragraph is about restitution of articles that were taken from colonies. 3 introduces the topic at hand: European museums are trying to come to terms with their colonial legacy by returning artefacts. 2 follows 3, providing the reason why this development has taken place. 1 then further describes the current situation: the legal obstacles this action could face. 4 concludes the paragraph by saying that other than these legal obstacles, institutions in France and Germany are seriously backing the move. Hence, the correct arrangement is 3214.