The correct answer is PARALLELISM
Parallelism refers to a rhetorical device that is used to coordinate ideas, arrange it in sentences, and point out relations. Sometimes, there are similar wordings used to highlight comparisons. In this case, "conscientious" and "conscience" are being paralleled.
The sentence which uses correct punctuation is C. In time, of course, all issues get resolved, but not necessarily in the way you would like.
In A, the comma before <em>he was concerned </em>should be a dash. In B, there should be a colon before <em>a flashlight, </em>not a semi colon. In D, there should be a comma before <em>yet, </em>and not a colon.
D I’m not sure though so if it’s something important I wouldn’t put that
