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 mall 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 gives 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 rain 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 according to the writer has become the agony of man?

Machines are their masters

The correct answer is Option (3) → Machines are their masters

The writer expresses concern that there is a risk of machines becoming the masters of humanity rather than serving as tools created to be man's servants. The idea is that humans may become increasingly dependent on machines to the point where machines have control over them, leading to what the author describes as the agony of man.