8.Which of the following best completes the passage below? At large amusement parks, live shows are used very deliberately to influence crowd movements. Lunchtime performances relieve the pressure on a park’s restaurants. Evening performances have a rather different purpose: to encourage visitors to stay for supper. Behind this surface divergence in immediate purpose there is the unified underlying goal of______ (A) keeping the lines at the various rides short by drawing off part of the crowd (B) enhancing revenue by attracting people who come only for the live shows and then leave the park (C) avoiding as far as possible traffic jams caused by visitors entering or leaving the park (D) encouraging as many people as possible to come to the park in order to eat at the restaurants (E) utilizing the restaurants at optimal levels for as much of the day as possible 答案：E，不明白为什么