题目

As shocking as the idea of baby birds growing up in a cigarette-filled home sounds, a new study suggests that some birds may benefit from putting the stuff from cigarette butts (烟蒂) into their nests. The nicotine(尼古丁) remaining in smoked filters (滤嘴) may serve as a natural insecticide( 杀虫剂) , driving harmful insects away from the nests and the baby birds living within. Tobacco plants produce nicotine because it defends against insects that would otherwise eat the plants.     The butts are undoubtedly smelly. But birds are actually quite fond of smelly chemicals, 世界贸易组织成立于（　　）。 [　　] A．1994年 B．1995年 C．1996年 D．1997年