What was an immediate impact of the Declaration of the Rights of Man and the Citizen? Americans adopted a constitutional system of government...

The only plausible answer to this question is answer choice 4, though the fall of the French monarchy was not an effect of the Declaration of the Rights of Man. The other answer choices, however, have nothing to do with the French Revolution, and the Declaration, issued by the revolutionary National Assembly in August of 1789, was an important part of this event. So while it is the only answer having anything to do with the French Revolution, it is not really correct. The early "liberal" phase of the Revolution, during which the Declaration was issued, established a constitutional monarchy with the Declaration as a statement of general principles. King Louis remained in power until almost four years later when he was executed, the Revolution by that point having taken a more radical turn toward establishing a republic. The reform-minded nobles and bourgeoisie who issued the Declaration of the Rights of Man did not, for the most part, argue that the King should be removed from power.