The activists’ energetic work in the service of both woman suffrage and the temperance movement in the late nineteenth century ______ the assertion that the two movements were inimical.
考查动词辨析。A项diffuse“扩散，传播”，B项undermine“逐渐削弱（信心、权威等），渐渐破坏”，C项support“支持，帮助，支撑”，D项underscore“强调，划线于……下”。根据句子可知，句子缺少一个谓语动词，由The activists’ energetic work in the service of both woman suffrage and the temperance movement（积极分子为妇女选举权和禁酒运动所做的积极工作）和the assertion that the two movements were inimical（这两个运动是敌对的断言）可判断，这两者的关系是“削弱”，B项符合。句意：19世纪晚期，积极分子为妇女选举权和禁酒运动所做的积极工作削弱了这两个运动是敌对的论断。因此，该题选择B项。
