单选题
Some studies confirmed that this kind of eye disease was ______ in tropical countries.
【正确答案】
B
【答案解析】prevalent流行的，盛行的[(+among/in)]they were brought up in the liberal atmosphere prevalent in the l900s；prospective预期的，即将发生的a prospective client；provocative挑衅的；perpetual永久的；长期的They hoped to live in perpetual happiness．