Listen to part of a lecture in an environmental science class.
Professor: Today we're going to talk about a surprisingly effective tool in combating climate change: beavers. Yes, the dam-building rodents. Recent studies show that beaver dams create wetlands that store significant amounts of carbon. When beavers build dams, they flood surrounding areas, creating ponds and marshes. The waterlogged conditions slow down the decomposition of organic matter, like leaves and wood, which means carbon gets locked in the sediment instead of being released into the atmosphere. Furthermore, these wetlands act as natural filters, improving water quality. They also provide critical habitat for many species, from fish to birds. Some researchers even call beavers 'ecosystem engineers' because of their profound impact. However, there's a catch. Beavers can cause flooding in agricultural areas, leading to conflicts with farmers. So, conservation groups are working on non-lethal solutions, like installing 'beaver deceivers'—pipes that control water levels without removing the dams. The goal is to balance ecological benefits with human needs.
❓ 题目 What is the main point the professor makes about beavers?
A. They are a major cause of flooding in agricultural areas.
B. They are a valuable natural ally in reducing atmospheric carbon.
C. Their dams are being removed to protect farmland.
D. They are the primary engineers of most wetland ecosystems.
✅ 正确答案
They are a valuable natural ally in reducing atmospheric carbon.