__________________________________________________________; a hungry man has to eat food to appease his hunger. Another example is the case of a sick person. He will be able to regain health only if he takes the prescribed medicine and follows the recommended diet strictly. If one wants to know how the moon looks like it is possible only if one sees it with one's eyes and not by another's description.
If someone is carrying a heavy load on his head another person can help him by relieving him of the burden but not so his pangs of hunger
The introductory line must introduce the ideas that are elaborated in the passage. The passage talks about how each man must take care of his own needs and nobody else can do it for him. The first example is about a hungry man and how only food can appease his hunger. Option (d) is the introduction to this example. Even if we carry a man's burden nobody can satisfy his hunger. It is also in keeping with the idea given in the entire passage about how the sick man can only get better if he takes his medicines regularly and also the analogy with the moon. Option (a) talks about money which is irrelevant here. Option (b) only talks of certain cases but this is true always. Hence it is eliminated. Option (c) is too vague.
Hence option (d) is the correct answer.