(单选题)

What is Darwin’s letter about?

A.The evolution of Yellowstone National Park.

B.His cooperation with an American geologist.

C.Some geological evidence supporting his theory.

D.His acknowledgement of help from a professional.

参考答案：D

参考解析：

细节理解题。根据第四段第一句“The letter was written by Darwin to thank an American geologist,...”可知，Darwin写这封信为了感谢地理学家提供给他一些相关地理方面的材料，D选项acknowledgement意思是感谢，他感谢来自专业人士的帮助，符合文意，所以A项、B项、C项错误。故选D。

知识点：阅读理解四选一英语专业基础知识阅读理解教师招聘-小学英语