参考答案

正确答案：D
解析：词义题型见第8段第一句：The division of work into components that could be measured and easily taught reached its apex in Ford’s River Rouge Plant in Dearborn，Mich．，where the assembly line came of age．(工作被分成了不同的部分，变得能被衡量且更易学会了；这种分工在密执安州的迪尔伯恩市的福特汽车制造厂的River Rouge厂达到了顶点；那里的生产流水线——)；根据句中说的“已达到了顶点”，came of age应不仅指“出现或发生”。应指“达到最有效的模式”；因此D为答案。