The correct answer is B indeed. It is an example of plain folks because the speaker appeals to the citizens of his town, and to the knowledge that he shares with the other members of the community. This strategy is quite basic, as shown by this example, because the author makes a claim that most people would agree with, without actually providing evidence or a series of logical arguments.
I believe the answer is A
Both options are technically grammatically correct, but the one that makes the most sense in this sentence is "when."
