题目内容：
根据以下材料，回答题。
According to the first paragraph, people usually believe that __________.
A．poor people in poor countries contribute to the imbalance of nature
B．rich people know how to protect the environment by taking actions
C．people in poor areas know a lot about the birth control
D．rich people in rich countries have done a lot to balance nature
参考答案：
答案解析：