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Hi Ali, I'll take a shot at diagramming it- although this might look more like a restatement of the set of facts. If opposable thumbs -> primate Lemur =lower If primate on Madagascar -> Lemur If living lower and diurnal -> lemur If higher -> evolved from diurnal lower This is a lot of complex statements- most of them have more going on than a simple "if x then y." Regarding (A), we know that the chimp evolved from a lower diurnal primate. However, we cannot say that that primate was a lemur. While we know that lemurs are the only living lower diurnal primates, it is possible that there were other ones in the past that were not lemurs. We can prove B is correct since we know that lemurs are the only primates on Madagascar, so there cannot be any higher primates indigenous to Madagascar.