The underlined word "dubious" (Line 2, Par

A．eighty per cent of American working people were employed in factories
B．twenty per cent of American intellectuals were employees
C．the percentage of intellectuals in the total work force was almost the same as that of industrial workers
D．the percentage of intellectuals working as employees was not so large as that of industrial workers

A．factory labors will overtake intellectual employees in number
B．there are as many middle-class employees as factory laborers
C．employers have attached great importance to factory laborers
D．the proportion of factory laborers in the total employee population has decreased