GRE考试

【单选题】 The primary topic of the passage is which of the following
A．(A) The origin of bioluminescence in plankton, predators
B．(B) The disadvantages of bioluminescence in microorganisms
C．(C) The varieties of marine bioluminescent life forms
D．(D) Symbiotic relationships between predators and their prey
E．(E) Hypotheses on the causes of bioluminescence in plankton

网考网参考答案：E
网考网解析：
The author first states that the reasons for bio-luminescence in underwater microorganisms is obscure and then proceeds to enumerate various hypotheses. 查看试题解析出处>>