It's really hard to tell yet. Certainly not d or e lol. There's a strange fight happening right now with regard to "Biden should step aside", Trump is guaranteed to beat Biden now unless something pretty newsworthy enters the cycle, something like "Biden ends his campaign" and it could have been a deliberate miss to put more pressure on biden to quit. So C might be a thing.

There's also the possibility that someone with power really wants him to win for some reason.

B, possible, but I don't see them missing. Maybe? Accidents happen, they're not omnipotent.

A, looks likely right now. But judging from history, it's not that common that it's just some random werido. Almost inevitably there are strange circumstances surrounding these things, for example, the guy that shot Ronald Regan had a brother who was having dinner with the son of then VP Bush the day it happened and the story was taken directly out of Taxi Driver. An aside, he has a YouTube channel now where he plays awful acoustic guitar songs, https://www.youtube.com/watch?v=H6GLrdscqyU