OG: Scientists say that, by bathing the skin cells in extracts of immune cells,

This question test our ability of grammatical construction. "by bathing the skin cells in extracts of immune cells" is a prepositional phrase (PP), so usage of that in underlined sentence is redundant. Similarly the main subject of clause should be Scientists / They.


Option-A & B - as explained above
Option-C : distort the meaning and passive form is unrequired
Option-D : Meaning error, 'as' is used for comparison, but not to indicate role/function, so it should be followed by clause
Option-E : Correct choice as the subject is they (scientist) and 'as' is used for comparison/reasoning.

in option E of the question, isn't pronoun "they" lead to logical predication error by acting as a potential antecedent to "scientists" and "human skin cells"? For different antecedents, different meanings are achieved, thus I think this option may be faulty.

Please help to clarify.