GMAT Sentence Correction (SC) | Re: Maxwell’s theory of Electromagnetism in 1865 was the first

Hi Mike,

I have two quick questions on this that I'd really appreciate some help on. The first is whether the '..., and ...' is being used to connect two Independent Clauses. Is option E the equivalent of "and Electroweak in 1961[was] the only other["unified field theory"] , as" with the bracketed portions omitted due to parallelism?

My second question is about the "because"/"as" split. I was under the impression that "because" is used to modify clauses, as it does in answers A,