Poem = (1)work of art +
(2)exploitation of musical characteristics of language(meter, rhythm, euphony, rhyme)
We're told that a novel is a work of art that exploits meter and rhyme. Both characteristics of a poem (above) have been satisfied, so the novel must also be a poem. (Choice C)
We're told that 90% of insomniacs drink coffee. We also know that Tom drinks a lot of coffee. Based on these two facts, we're told that Tom is quite likely an insomniac.
So, we know that if there are 10 insomniacs, then 9 of them will drink coffee.
We do not know, however, that if there are 10 people who drink coffee, that nine of them will be insomniacs. In other words, we have no idea of the percentage of people who drink coffee who are insomniacs. There might be many people who drink coffee who are not insomniacs, but if it's a given that you are an insomniac, then it's likely that you drink coffee.
This is why C is the answer. We know nothing as to whether people who drink coffee are likely to be insomniacs, and yet the conclusion of the passage relies on that exact information to form its conclusion. As for D, that isn't the problem. If we were told that 90% of people who drink coffee are insomniacs, and that Tom drinks coffee, it would be valid to rely on the group information to draw the inference that Tom is likely an insomniac. So, the problem is not relying on group info to form a conclusion about an individual, but instead relying on faulty information within the passage.
We're told that most peoples' dreams do not predict the future, though some peoples' dreams do. Because most peoples' dreams do not predict the future, it's unreasonable to believe that those people who do have predictive dreams have ESP.
Similarly, in choice D we're told that most people who take Aspirin do not die prematurely, though some people who take Aspirin do die prematurely. Because most people who take Aspirin do not die prematurely, it's unreasonable to conclude that Aspirin is dangerous.
The flaw is the same, in that it dismisses the possibility of what is occurring in the minority, simply because it's not occurring within the majority.
The problem with choice B is that the word "many" is used to describe both groups so we do not know which group is in the majority. In order to match the flaws, we need both a majority and a minority group.