Well the Industrial Revolution is known for taking hand-labor, and turning it into machines doing all of the work, so it would not be B. or C.
It did not really give them any more free time, for they had been upper-middle class and already had disposable income and free time.
So I do believe the best answer is A. Because they could use political power to enforce regulations; or I should say it made it easier.
Hope I helped, and good luck!
LBJ who was the president that time authorized a highly classified reconnaissance so that he can gather intelligence on communist activities in Cambodia. While Nixon was persuaded so that he can use full flung aerial for the military action because of enemies of Cambodian.
