Which quantity can be described as changing at a constant rate? A. The number of people involved in a shared email, if each person must share the email they received with 7 new people. B. The number of players left in a tournament when half of the players are eliminated each turn. C. A Flu virus, which will infect 3 new people for every 1 person infected. D. The total number of Yogs used for a bonfire, if 5 new logs are added each hour