Indelible means permanent. An indelible moment would be something like going to a job interview and the first impression you make is indelible, it can't be changed or redone.
You have to give us some more information...
Oakland is supposed to be the underdog in the game tommorow light, so the team that is supposed to win is the Kansas City Chiefs.
C. an understood you, because usually you is the subject in the sentence, but it is understood without it.
