A study of 20 overweight men revealed that each man experienced signif

KAPLAN OFFICIAL EXPLANATION:

Step 1: Preview the question stem.
We see, quite clearly, that we're dealing with an Assumption question. So we can immediately adopt an "assumption mindset," which means that before even reading the stimulus, we know that the conclusion will be lacking an important piece of supporting evidence. We now turn to the stimulus, already on the lookout for this missing link.

Step 2: Read the stimulus.
Sentence 1 introduces a study of 20 men using a food supplement product, resulting in weight loss for all 20. Sentence 2 describes how they used it: once a day, for 3 months, after morning exercise. So far so good; it feels as if we're building up to something. The key word clearly usually indicates that some sort of conclusion follows, and in fact it does: Sentence 3 says that anyone who has one portion of the product daily for 3 months will lose weight, too.

You must read critically! The conclusion doesn't say that anyone who follows the same routine as the 20 men will have the same results; it says that anyone who simply consumes the product will have the same results. You should have begun to sense the inevitable lack of crucial information at this point. The evidence in sentence 2 describes a routine that includes taking the supplement after daily exercise, whereas the conclusion focuses primarily on the supplement and entirely ignores the part about the exercise. The conclusion, therefore, doesn't stem logically from the evidence in the first two sentences. This blends seamlessly into Step 3.

Step 3: Prephrase an answer:
As expected, it's beginning to look like the argument has a serious shortcoming. Of course, we expected this because we previewed the question stem before reading the stimulus. In simplistic terms, the argument proceeds like so: "A bunch of guys did A and B for 3 months and had X result. If anyone does A for 3 months, that person will experience X result, too." Sound fishy? You bet. The author must be assuming that A (the product), not B (exercise), must be the cause that leads to the result. If not (here is the Denial Test), the conclusion makes no sense.

So, you might prephrase the answer like this: "Something about the exercise thing needs to be cleared up" That's it Did you think your prephrasing had to be something fancy and glamorous? Well, it doesn't. So, with our vague idea of a possible assumption, we can turn to Step 4.

Step 4: Choose on answer.
Because we were able to prephrase something, it's best to skim the choices looking for it. And, lo and behold, there's our idea, stated in choice (C). (C) clears up the exercise issue. Yes, this author must assume (C) to make the conclusion that eating SlimDown alone will cause people to lose weight.

At this point, if you're stuck for time, pick (C) and move on. If you have more time, check the remaining choices quickly, to double-check that none of them fits the bill. Be ready to dismiss the other choices unless they make a strong case for themselves. Since the difficulty in Critical Reasoning is often in the choices (rather than the stimulus), you can't let them make you indecisive.

Could you please explain more about eliminating choice A?
A -> If the males discontinue SlimDown program and will gain weight then clearly, SlimDown is the only contributor of losing their weights. So, choice A eliminates all other possibilities like diets, exercise, etc.
Option C only talks about exercise, but there may be other factors as well, which it ignores.

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