题目内容：
Directions：In this part,you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1．For questions 1-7 choose the best answer from the four choices marked[A]，[B]，[C]and[D]．For questions 8-10,complete the sentences with the information given in the passage． 
注意：此部分试题请在答题卡1上作答，8～10题在答题卡1上。
根据以上短文，回答下列问题
According to World Health Organization，how many people are killed by outdoor air pollution?
[A]3 million
[B]2.1 million
[C]1.6 million
[D]3.2 million
参考答案：
答案解析：