This is my analysis of E (and nicely explained, singh181); if the OA is E, this is not a great question. Still a great conversation topic, though!singh181 wrote: E "that" modifies the "electorate", but we are interested in the figure in 1996. E means that "electorate" fell to 40%, not the figure, which was 55% in 1972.
Run-on sentences, though, only happen when two independent clauses are joined without a coordinating conjunction or a semicolon. Choice A is either just incorrectly punctuated or the second independent clause is actually just a fragment (depending on how you want to look at it).
