Question: Liver Disease

Comment on Liver Disease

I could not understand the reasoning for option D -- it already says 'not the result of'
should we always apply negation technique to all the likely options to verify ?
gmat-admin's picture

If an answer choice already seems like a necessary assumption, you can just select it. That said, applying the negation technique is useful to help you be even more certain.

Hi Brent. Option D says small lobe is not caused by medications. If this is true, it does not mean that we don't have other causes that may cause the smallness of lobe and thus we can't be sure that the smallness will cause to H.
gmat-admin's picture

Sure, it's quite likely that there are other things that cause liver smallness, but we're trying the determine the cause of hepachrinosis.

So, it may be that something else cause liver smallness, and, as a consequence, that liver smallness causes hepachrinosis.

If we negate answer choice D, the argument is completely ruined. So, it must be the correct answer.

Help me understand... answer choice D seems to make multiple assumptions. One being that the twin(s) are taking medication and the other that smallness is affected by the medication. I have not yet watched all of tb videos, but Is this not something to look out for?
gmat-admin's picture

The important thing to remember in an assumption question is that the question is asking for AN (not THE) assumption that's required by an argument. In pretty much any argument, there are tons of necessary assumptions. So, if ONE assumption holds true, we can't then say the conclusion is 100% guaranteed.
However, WITHOUT the assumption, the argument's conclusion CANNOT follow.

Here's an example of what I mean:

Joe makes birdhouses for a living. He makes 3 birdhouses per day, and he cannot make more than 3 per day. One day, a Costco representative says that Costco wants to sell Joe's birdhouses. In the agreement between Costco and Joe, Joe agrees to produce 6 birdhouses per day. So, if Joe hires Jane to make birdhouses with him, he will meet all of the terms of the agreement.

What's AN assumption upon which this argument relies? There are plenty!

One assumption is that Jane is able to produce at least 3 bird houses per day.
However, even if it's 100% true that Jane is able to produce at least 3 bird houses per day, we can't then say that the conclusion is guaranteed. There are plenty of other factors (sickness, death) that could prevent Joe (and Jane) from making 6 birdhouses per day.
However, if Jane is NOT able to produce 3 bird houses per day, then the conclusion is killed.

Likewise, for this question, if the disease DID cause the decrease in the lobe's size, then that would kill the conclusion that the disease is caused by decreased lobe size.

Does that help?

please explain

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