Critical Reasoning

Among people who experience migraine headaches, some experience what doctors call "common" migraines, whereas others experience "classical" migraines. Siblings and spouses of common migraine sufferers are themselves twice as likely as the general population to experience common migraines. Siblings of classical migraine sufferers are four times more likely than the general population to experience classical migraines, whereas spouses of classical migraine sufferers are no more likely than the general population to experience such headaches.

The information above provides the most support for which of the following hypotheses?

(A) Susceptibility to classical migraines is more dependent on hereditary factors than is susceptibility to common migraines.
(B) Unmarried adults are more likely to suffer from classical migraines than they are to suffer from common migraines.
(C) People who do not experience migraine headaches are unlikely to have spouses who are migraine headache sufferers.
(D) Children of people who suffer from common migraines are not more likely than the general population to experience a common migraine.
(E) Between one-quarter and one-half of the general population suffer from either common or classical migraine headaches.

Oa is A; Two question :
1. Is the correct answer choice typical of such questions where we look for MUST be true or reasonably correct answer choices ?

2. Why B is wrong; I can feel it but want to know precise reason to destroy.

- Migraines can be "common" or "classical"

- Siblings + Spouses 2x likely to get "common"

- Siblings 4x likely to get "classical"
- Spouses no more likely to get "common"

Question Rephrase: How come? (possible causes)

Prediction: "Common" may be environment-caused or can be somehow "spread"; "classical" may be genetic

A is quite clear as the best match for our prediction.

1. The choice here is correct because it best EXPLAINS the evidence (why are siblings more likely to get "classical" migraines?) None of the other choices offer a reason for this.

2. This is incorrect because it does not explain why siblings are 4x more likely than spouses to get "classical" migraines, though they have an equal chance of getting "common" migraines.

Vivian I choose A for reasons you splendidly explained.
I have analyzed the rest of the choices. Could you please correct me if I am wrong:
I crossed B for the simple fact that: the question stem compares an individual's susceptibility to migraine to general population, whereas in B the fact is not clearly stated whether Unmarried adults are being compared to general population or not.

C be eliminated from the fact that the question stem states only two types of migraines whereas there could be other types too. C seems to assume that these two are the only types of migraines.

D: Stimulus restricts the targets of common migraines to "siblings" and "spouse" and doesn't include children.

E: Even if the facts are to be true, I think this choice just reverses the ratios: one-half (stimulus) vs one-quarter suffer from common migraine and one-quarter (stimulus) vs one-half suffer from classical migraine headaches.