(A) is not a valid argument — just because viruses flourish in warm places doesn’t mean that being in cold air can’t cause someone to catch a cold. It also concludes that a causal relationship between A (cold air) and B (catching a cold) is inaccurate, whereas the stimulus is concluding that a causal relationship between A and B is accurate.

(B) doesn’t talk about A causing B by causing C which causes B. The airline doesn’t fly from Halifax to Washington because it doesn’t offer any direct or connecting flights — the answer choice doesn’t introduce any extra factor C.

(C) isn’t a valid argument — just because overfertilization contributes to lawn disease doesn’t mean it’s the primary cause. Thus, although it uses a somewhat similar structure — A (overfertilization) causes B (lawn disease), because A causes C (rapid growth) and C leads to B — it is not parallel.

(D) argues that it is incorrect to say that A (inferior motor oil) cannot cause B (poorer mileage), because A causes C (engine valve deterioration), and C can cause B. This is the same reasoning as the stimulus.

(E) doesn’t make an argument about causation. It just talks about Alexander the Great’s relationship to Plato.