<p>During the labor dispute, barrels of potatoes were emptied across the (highway , and they thereby blocked it to all traffic.)
(A) highway , and they thereby blocked it to all traffic
(B) highway and therefore blocking it to all traffic
(C) highway , by which all traffic was therefore blocked
(D) highway , and therefore this had all traffic blocked
(E) highway , thereby blocking all traffic</p>
<p>The answer is (D) . But isn't thereby a conjunctive adverb and should be placed after a semicolon ? Can someone please explain this and why each of the other options wouldn't work? Thanks (: </p>
but could you explain why it is correct?</p>