Why isint A right still?

Hi @Motunrayo-Bamgbose-Martins, This question is asking you to pick the answer choice which is an assumption required by the argument. This means you need to pick the answer choice which MUST be true in order for the conclusion of the argument to be true. Answer (A) is not correct because it does not have to be true in order for the conclusion to work. The conclusion is that the discovery proves that schizophrenia is caused by damage to the brain. The fact that a person with schizophrenia has a smaller brain than someone not suffering from it does not help prove this. You could also eliminate this choice by noticing that it goes beyond the scope of the question. The paragraph talks about the brains of identical twins but this one says people with schizophrenia have smaller brains than everyone else. There's no basis for this. Finally, to answer your question of if certain areas are small, doesn't that make the overall brain size smaller, that is not necessarily true. All we know is that some parts of the brain are small. Maybe, other parts of the brain got bigger to fill in the space. It is not necessarily true that the overall brain is smaller.

thank you