<p>The filibuster on voting-rights legislation went on for three days and NIGHTS; SENATORS SLEPT WHEN THEY COULD on benches in the hall.</p>
<p>A) nights; senators slept when they could
B) nights, which meant senators sleeping when possible
C) nights; therefore, it meant that senators would sleep when possible
D) nights and therefore the senators would be sleeping when able to
E) nights; with senators sleeping when they could</p>
<p>(B) has the wrong tense. (C) has redundant causation. (D) doesn’t properly link two independent clauses. (E) is wrong because what follows the semicolon is not an independent clause.</p>
<p>It’s not an established term, but I used it to mean that choice (C) twice indicated the causal link: “therefore, it meant” is redundant. “it meant” shows causation, and “therefore” does also. </p>
<p>It’s similar but more obvious in this example: “Bob is hungry. For this reason, therefore, he ate.” </p>
<p>There is almost double redundancy here because the semicolon itself can indicate causation in some cases.</p>