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OK, answer choice B: This is actually an if-then statement as well. If we translate B into "if-then" wording, we get "If a person does NOT suffer any damage to any language centre in the brain, then his or her linguistic capabilities are NOT impaired". This is a negation of one part of the evidence (which means, incidentally, that it does NOT follow logically from that piece of evidence), but it is not the assumption that we need. As I discussed earlier, the assumption we need is: "If no language centres were damaged (by a serious stroke on the left side), then there ARE no language centres on the left side."
It is actually quite common for some or most of the answer choices in an assumption question to be "if-then" statements, even if they are not worded that way. It is fairly common to find that the correct assumption (or one of the assumptions) is an "if-then" statement. For example, the correct answer to Q. 32 on p. 476 of OG 11
is "Bicycle racers do not generate a strong demand for innovations that fall outside what is officially recognized as standard for the purpose of competition." Logically, this is actually an "if-then" statement, because it means: "If an innovation falls outside what is officially recognized as standard for the purpose of competition, then bicycle racers do not generate a strong demand for it."
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