A、Your folks. B、Polite drivers. C、Traffic jams. D、Pains in head. C文章开头提到在洛杉矶驾车时经常会遇见的几种情况，如交通堵塞、人流车流拥挤、不礼貌的司机等。四个选项中只出现了交通堵塞这一项。

(30)If you have ever driven in Los Angeles,you know that people don’t cooperate terribly well. Traffic jams, folks cutting folks off, people shouting at you out their windows.. .it’s a real headache. We would all do a lot better— at least, we would all move through the traffic jam a lot faster—if we were ants. Why ants,you may ask. That’s what Ian Couzin of Princeton University wanted to know. You may have seen films of huge numbers of South American Army Ants moving across the grass on raids and coming back with all sorts of things to eat. So why don’t they all crash into each other and suffer the traffic jam the way humans do? (31) One answer Couzin found is that army ants follow a simple procedure: everybody coming home has the right-of-way. It results in a stream of home-going ants passing unobstructed through the center of a crowd of out-going ants. Among other things, this means raiding parties can go any direction from the anthill,because nobody has to remember some complicated rule about turning left or turning right. Also,the guys bringing home the things will always be protected on both sides by out-going ants. Would this work in Los Angeles? Probably not. (32) Thousands of human beings just can’t be made to follow a behavioral rule like that. Somebody would try to get a little bit ahead,then somebody else would see that and get angry,and pretty soon,you’re back to Los Angeles traffic. For better or worse,people don’t think like ants.
30. What would you face while driving in Los Angeles?
31. Why don’t ants suffer a traffic jam?
32. Why can’t people in Los Angeles copy the example of ants?