It is plain that in the year 2020 everyone will have at his elbow several times more mechanical energy than he has today．There will be advance in biological knowledge as far reaching as those that have been made in physics．We are only beginning to learn that we can control our biological environment as well as our physical one．Starvation has been predicted twice to a growing world population：by Malthus in about 1800．by Crookes in about 1900．It was headed off the first time by taking agriculture to America and the second time by using the new fertilizers．In the year 2020，starvation will be headed off by the control of the diseases and the heredity of plants and animals--by shaping our own biological environment．
Now I come back to the haunting theme of automation．The most common species in the factory today is the man who works or minds a simple machine--the operator．By the year 2020，the repetitive tasks of industry will be taken over by the machines，as the heavy tasks were taken over long ago；and the mental tedium will go the way of physical exhaustion．Today we still distinguish，even among repetitive jobs，between the skilled and the unskilled；but in the year 2020 all repetition will be unskilled．We simply waste our time if we oppose this change；it is as inevitable as the year 2020 itself．
Repetitive tasks in industry lead to__________．
A.physical exhaustion
B.mental stimulation
C.mental exhaustion
D.extinction