Gigantic passenger planes currently being developed will have enough space to hold shops and lounges in addition to passenger seating. However, the additional space will more likely be used for more passenger seating. The number of passengers flying the air-traffic system is expected to triple within 20 years, and it will be impossible for airports to accommodate enough normal-sized jet planes to carry that many passengers.

Which one of the following most accurately states the conclusion drawn in the argument?

Scientist: To study the comparative effectiveness of two experimental medications for athlete’s foot, a representative sample of people with athlete’s foot were randomly assigned to one of two groups. One group received only medication M, and the other received only medication N. The only people whose athlete’s foot was cured had been given medication M.

Reporter: This means, then, that if anyone in the study had athlete’s foot that was not cured, that person did not receive medication M.

Which one of the following most accurately describes the reporter’s error in reasoning?

Paleontologist: Plesiosauromorphs were gigantic, long-necked marine reptiles that ruled the oceans during the age of the dinosaurs. Most experts believe that plesiosauromorphs lurked and quickly ambushed their prey. However, plesiosauromorphs probably hunted by chasing their prey over long distances. Plesiosauromorph fins were quite long and thin, like the wings of birds specialized for long-distance flight.

Which one of the following is an assumption on which the paleontologist’s argument depends?

Music professor: Because rap musicians can work alone in a recording studio, they need not accommodate supporting musicians’ wishes. Further, learning to rap is not as formal a process as learning an instrument. Thus, rap is an extremely individualistic and nontraditional musical form.

Music critic: But rap appeals to tradition by using bits of older songs. Besides, the themes and styles of rap have developed into a tradition. And successful rap musicians do not perform purely idiosyncratically but conform their work to the preferences of the public.

The music critic’s response to the music professor’s argument

Speaker: Like many contemporary critics, Smith argues that the true meaning of an author’s statements can be understood only through insight into the author’s social circumstances. But this same line of analysis can be applied to Smith’s own words. Thus, if she is right we should be able, at least in part, to discern from Smith’s social circumstances the “true meaning” of Smith’s statements. This, in turn, suggests that Smith herself is not aware of the true meaning of her own words.

The speaker’s main conclusion logically follows if which one of the following is assumed?