The Parting of Lot and Abraham is about their literal parting - Abraham took his family to Canaan, as God wanted him to, whereas Lot went to Sodom, and defied God's wishes. Now, having this in mind, maybe this mosaic does symbolize B. heaven, as Abraham and his family would go to heaven eventually, because they obeyed God's orders and wishes.
Answer: It means to seem less important or impressive when compared to something or someone else. Less enjoyable because of saddness, fear, or worry; to cast shadow over something.
