The Joint Chiefs of Staff were not officially assembled until after World War Ⅱbut they ______ from an earlier attempt by Theodore Roosevelt to create a board that would work and plan jointly across the armed forces.
根据逻辑结构可知，西奥多·罗斯福在二战期间建立了一个决议会来对兵力进行联合管理，在这之后渐渐形成了参谋长联席会议，D项evolved（发展）最合适意，选D。