So far this year, twenty elected legislators
had opted not to run for reelection in the aftermath of the Bathwater scandal.
I am really bad at Verb-Tenses, however IMO So far this year changes the verb tense scenario, instead of had we need have opted not to run to denote that this action has taken place before now. Also the act of running for re-election happened after the scandal, therefore, as per the timeline, the scandal took place first and afterwards the legislators decided not to run for re-election.A. had opted not to run for reelection
(Incorrect verb tense)B. had opted to not run for reelection
(incorrect verb tense)C. have opted to not run for reelection
(don't know why but to not run for sounds awkward, would be glad if someone can throw light on why this option is wrong)D. have opted not to run for reelection
(correct)E. have opted to not run again for reelection
(redundancy: run again, re-election)I hope my answer and my explanations have some merit. Eagerly waiting for OA.