71. For the sake of the logic and coherence of this paragraph, Sentence 2 should be placed:

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

Sentence 2 means "Silkworms are portable, therefore, transportation is very cheap." Sentence 1 puts forward two threat factors. Sentence3 emphasizes "but Parmesan thinks that the butterfly checkerspot is a perfect assisted move species", so sentence2 should be placed after sentence3 to express the first reason, and sentence4 puts forward the second reason, that is, "she does not think that the butterfly is not enough to endanger new species. place of residence".