【正确答案】 B

【答案解析】[听力原文]
   The Federal Aviation Administration, or FAA, the government agency that regulates civil aviation in the United States, announced new rules this month to fight pilot tiredness. The new guidelines, which will go into effect in two years, call for reducing the number of pilots' on-duty hours and giving them a 10-hour rest period between shifts, so they can get at least 8 hours of sleep. The new rules apply to only pilots of passenger airlines. FAA determined that including pilots who fly cargo planes a large portion of the aviation industry would add too much to the cost of carrying out the changes. But the Independent Pilots Association has taken legal action asking the government to set one level of safety for all pilots.
   What is the main purpose of the new rules?
细节推断题。由new rules this month to fight pilot tiredness. 可知，这个月的新规定是防止飞行员疲劳驾驶。也就是说新规定的目的是防止飞行员疲劳驾驶，故选B。