let us take a look at the main conclusion --
schizophrenia is caused by damage to the physical structure of the brain.
this is a cause and effect statement. We can write this as --
damage to the physical structure of the brain --> schizophrenia
One of the simplest ways to approach an assumption question would be to figure out a flaw in the argument. Negating that flaw would lead us to an assumption made in the argument.
Commonly found patterns of flaws in causal statements are reverse causation (Effect --> Cause) and alternate cause (Another cause --> effect).
let us take a look at the answer options --
Option A - Incorrect
Not a proper comparison. We are comparing the brains of IDENTICAL TWINS -- from this we are deriving our conclusion that physical damage to the brain causes schizophrenia.
Option B - Incorrect
If the smallness of the brain in the identical schizophrenic twin is due to "medications", this destroys the argument by providing an alternate cause.
If it is due to schizophrenia itself, this tells us that the effect led to the cause (Reverse causation) -- again weakens the argument.
By denying both these flaws, option B states an assumption.
Option C - Incorrect
Not a proper comparison. We are comparing the brains of IDENTICAL TWINS -- this helps us to control for other factors that might impact the brain size. We are not comparing the brain sizes of twins to those of other people.
Option D - Incorrect
this directly contradicts the conclusion -- which says that different size (smaller brain size due to physical damage) is something that causes schizophrenia
Option E - Incorrect
Not relevant to the argument. the argument is concerned with WHAT CAUSES schizophrenia, not HOW LIKELY it is to occur.
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Crackverbal Prep Team
www.crackverbal.com