In which of these situations do the quantities combine to make 0? A. Kathy receives $20 as a gift. She gives half of her $20 to a friend and keeps the rest for herself. B. A player in a game earns 4 points for getting an answer right. She then earns 4 points for making it around the board. C. In the morning, the temperature rises 30 degrees. In the evening, it falls by 30 degrees. D. A hot air balloon rises 40 feet. It then rises another 40 feet.
