Here we have a strengthen with necessary premise question. Remember that a premise is necessary for a conclusion if the falsity of the premise guarantees or brings about the falsity of the conclusion. First we check to see if the answer choice strengthens the passage, and then, if it does strengthen, we negate the answer choice to see if its negation makes the argument fall apart. If the answer choice does both those things then it is our correct answer.
Our conclusion is: "North American children can be made physically fit only if they participate in school calisthenics on a daily basis."
Why? We are told that in Europe school children devote time during every school day to calisthenics. We are told that North American schools rarely offer a daily calisthenics program. The argument then explains that tests prove that North American children are weaker, slower and shorter-winded than European children.
Answer choice (A) states: "All children can be made physically fit by daily calisthenics."
So, we can rewrite this in Sufficient & Necessary form: "If given daily calisthenics, then a child can be made physically fit."
The conclusion, rewritten in Sufficient & Necessary form states: "If a child is made physically fit, then they participated in school calisthenics on a daily basis."
Answer choice (A) is merely stating that daily calisthenics is a sufficient condition to becoming physically fit, i.e. it is not necessarily the ONLY way to become physically fit. Whereas, the conclusion states that daily calisthenics is a necessary condition to being physically fit, i.e. there is no other way to become physically fit. So, clearly answer choice (A) does not strengthen the argument.
Answer choice (B) states: "All children can be made equally physically fit by daily calisthenics."
Okay so we can rewrite this to be: "If given daily calisthenics, then a child can be made equally physically fit.'
Again, we have the same problem. Here, daily calisthenics is a sufficient condition, whereas the conclusion of the argument is that there is no other way to become physically fit than to be given daily calisthenics. Further, we never discuss being "equally physically fit" in the argument. It is irrelevant.
Answer choice (D) does strengthens the argument. "School calisthenics are an indispensable factor in European children's superior physical fitness," i.e. school calisthenics are a required (necessary) factor. This strengthens the argument because then we can assume that school calisthenics are an indespensible factor for North American children, as well, meaning that in order for North American children to be made physically fit, they must participate in school calisthenics on a daily basis, i.e. the argument's conclusion.
Next, we must negate the answer choice and see if its negation would make the argument fall apart.
Negation: "School calisthenics are not an indispensable factor in European children's superior physical fitness." If this were true, then school calisthenics are not a necessary factor in European children's superior physical fitness, which, in turn, means that North American children do not necessarily have to participate in school calisthenics on a daily basis to be made physically fit. Thus, answer choice (D) both strengthens the argument and its negation makes the argument fall apart. This is why answer choice (D) is the correct answer.
Hope that helps! Please let us know if you have any more questions.
stormbeelerNovember 10, 2015
I went with B assuming that all introduced sufficient. Does it not do that here because of the context in which it was used? Thanks.
rweyerApril 8, 2018
Wouldn't B just be restating the conclusion of the passage? of course the question stem is asking us which one of the following is assumed. B wouldn't be an assumption since it has been stated.
rweyerApril 8, 2018
Nevermind I see what I did wrong.
cayleyJuly 12, 2018
When there are two answer choices that are similar (like A and B), I am suspicious that test makers formulated them to be trap answers. Because of that I usually eliminate them as a time saver. I know that's just a hunch, but is it a habit I should break or am I in fact correct in assuming the answer choices are usually wrong? Thanks.
AnitaJuly 12, 2018
@cayley It's best not to eliminate answers just because they're similar. One of them may be correct! Just evaluate each answer of its own accord.
