定位在"through 1840....whereas other household members were only indicated by the total number of persons counted in various categories, including occupational categories."
也就是说 the members的信息是包含了occupational 的类别的。B选项中说people(这里就是household members的近义词) engaged in nonfarming occupations,就是包含了职业分类信息的人数啦~所以是正解