The third great defect of our civilization is that it does not know what to do with its knowledge. Science has given us powers fit for the gods, yet we use them like small children. For example, we do not know how to manage our machines. Machines were made to be man's servants; yet he has grown to dependent on them that they are in a fair way to become his masters. Already most men spend most of their lives looking after and waiting upon machines. And the machines are very stern masters. They must be fed with coal, and given petrol to drink, and oil to wash with, and they must be kept at the right temperature. And if they do not get their meals when they expect them, they grow sulky and refuse to work, or burst with rage, and blow up, and spread ruin and destruction all round them. So we have to wait upon them very attentively and do all that we can to keep them in a good temper. Already we find it difficult either to work or play without the machines, and the time may come when they will rule us altogether, just as we rule the animals.
What should be the expected behavior to keep machines in good temper?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Wait upon them attentively
The writer says that machines sulk, refuse to work or blow up if they are not looked after, and so "we have to wait upon them very attentively and do all that we can to keep them in a good temper". To wait upon someone is to serve and attend to them.
Why the Other Options are Incorrect?
Option 1: Leave them alone — Incorrect. Contradicted: machines left without their "meals" of coal, petrol and oil refuse to work or burst with rage.
Option 2: Let them work on their own — Incorrect. Contradicted: machines need constant care: feeding, oiling and the right temperature. They cannot be left to themselves.
Option 3: Allow them human company — Incorrect. Not mentioned: company is not what machines need; the passage speaks of serving them, not of keeping them company.