31. The primary purpose of the passage is to discuss the:
Your Answer is
Correct Answer is D
Explanation
The first paragraph indicates that the reason for pika's gradual demise is climate warming, and the second paragraph is the living environment of pika. The following paragraphs explore the reasons for the decline in the pika population.
Item D: In line with the purpose of the article.
Item A: The way scientists record the number of pikas in different places is not the main point.
Item B: The role of pika's social behavior in adapting to changing environments does not mention the social behavior of pikas.
Item C: The reason for the disappearance of pika and the countermeasures of the scientists, and the countermeasures of the scientists are not mentioned.