Hi UrFellow,

I'd go with B too. The reason is as follows :

Conclusion : Affected Animals can be cured to the disorder by being treated with the Silicon based compound.

Premise : Because silicon-based compound binds to aluminium and prevents it from affecting the brain tissue.


(A) Animals with the disorder have unusually high but invariable levels of aluminum in their brain tissue. -- For an assumption this is not relevant

(B) Aluminum is the cause of the disorder rather than merely an effect of it. --- A good assumption as there could be sideeffects of aluminium in the brain which could be causing the behavioural disorder. But as this statement has ruled out that option and says that aluminium is the only factor which causes that disorder.

(C) Introducing the compound into the brain tissue has no side effects. ---well there could be no side effects but there is a hole big enough in this statement as this does not prove that the "disorder has occured due to aluminum ".I can fit my own assumption and say that aluminium is just present in the brains of animals with already behavioural disorder it would still be correct and will go against the arrived conclusion. So thats why this option is wrong

(D) The amount of the compound needed to neutralize the aluminum in an animal's brain tissue varies depending upon the species. -- we are bothered about animals as whole not a particular species. so purge it.

(E) Aluminum is never present in normal brain tissue.--its weakening the conclusion. purge this too.

Hope it helps

thank you very much! it helps a lot!