Read the excerpt below from the short story “Rules of the Game” by Amy Tan and answer the question that follows. Vincent got the chess set, which would have been a very decent present to get at a church Christmas party, except it was obviously used and, as we discovered later, it was missing a black pawn and a white knight. My mother graciously thanked the unknown benefactor, saying, “Too good. Cost too much.” At which point, an old lady with fine white, wispy hair nodded toward our family and said with a whistling whisper, “Merry, merry Christmas.” What motivates the speaker’s mother to “graciously [thank] the unknown benefactor”?