【正确答案】 A

【答案解析】[听力原文]
Narrator
Listen again to part of the lecture. Then answer the question.
Professor
Wetlands have their own unique ecosystems with plants and animals with special and interesting adaptations...very exciting, but it"s not what we"re talking about today...Ummm...where was I?
Male student
Farmers moved south?
Narrator
Why does the student say this:
Male student
Farmers moved south?