C,D,E are out because we need Neanderthals as the subject of sentence. Neanderthals should be the subject because "so were probably without language" is referring to Neanderthals.
A is out because it is using "those" to refer Vocal tract and that is wrong.
I think B compares Neanderthals with an ape, lacking agreement in number. I would have also preferred a construction with the subject "Neanderthals" as you suggested.
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