The correct option is A And
Conjunctions are words that link other words, phrases, or clauses together. Correlative conjunctions are pairs of conjunctions that work together. Some examples are either/or, neither/nor, and not only/but also. The given sentence requires the use of correlative conjunction in order to join subjects carrying equal weight in the sentence i.e. knave and scoundrel.'Both' refers to the whole pair and is equivalent to "one and the other". The combination both/and indicates that the two items are equally presented and included. Hence Option A is correct. Option D can be ruled out as 'or' indicates that there is a choice and only one can be selected while in the sentence 'both' has been inferred. Option C is ruled out as well. Since 'nor' is usually used with 'neither' in order to indicate that neither of the two choices can be selected while in the sentence two items are equally presented. The conjunction 'but' is used to suggest a contrast but it cannot be used along with 'both' which is used in order to join subjects carrying equal weight in the sentence. Thus Option B can be ruled out.