Passage Two：Questions 16 to 20 are based on the following passage.Sport is not only physically challenging, but it can also be mentally challenging. Criticism from coaches, parents, and other teammates, as well as pressure to win can create an excessive amount of anxiety or stress for young athletes (运动员). Stress can be physical, emotional, or psychological, and research has indicated that it can lead to burnout. Burnout has been described as dropping or quitting of an activity that was at one time enjoyable. The early years of development are critical years for learning abut oneself. The sport setting is one where valuable experiences can take place. Young athletes can, for example, learn how to cooperate with others, make friends, and gain other social skills that will be used throughout their lives. Coaches and parents should be aware, at all times, that their feedback to youngsters can greatly affect their children. Youngsters may take their parents’ and coaches’ criticisms to heart and find a flaw (缺陷) in themselves. Coaches and parents should also be cautious that youth sport participation does not become work for children. The outcome of the game should not be more important than the process of learning the sport and other life lessons. In today’s youth sport setting, young athletes may be worrying more about who will win instead of enjoying themselves and the sport. Following a game, many parents and coaches focus on the outcome and find fault with youngsters’ performances. Positive reinforcement should be provided regardless of the outcome. Research indicates that positive reinforcement motivates and has a greater effect on learning than criticism. Again, criticism can create high levels of stress, which can lead to burnout. 第16题：An effective way to prevent the burnout of young athletes is ________. A) to make sports less competitive B) to make sports more challenging C) to reduce their mental stress D) to increase their sense of success