I would think "A" is a good way to proceed. This might be a silly question, but I wonder how it affects us if we send this reminder message to everyone versus just the people in our sample who we know have not responded yet. I know that maybe some of the people who did previously respond might get confused and possibly try to respond again. I would be interested in seeing if they update their answers or if they stay consistent. Any statistical insights on this?

EDIT: I thought about this some more and considered that sending out a reminder message to everyone may be akin to starting a new survey using a non-random sample. But by reaching out to just nonrespondents, maybe it’s okay.