单选题 A spider conserves its energy ______.

A、 because it constructs new webs daily
B、 as it walks over the strands it lays
C、 by eating its own web protein and then re-using it in the new web
D、 by eating only in the evening

【正确答案】 C

【答案解析】作者在第三段第一和第二句中介绍说："The spider conserves energy by recycling web protein．It simply eats its own web each evening and re-uses it to manufacture new silk"，可见[C]是正确答案。而[A]，[B]和[D]均不确切。