18.Which of the following best describes the

　　relationship of the second paragraph to the first？

　　（A）The second paragraph relies on different

　　evidence in drawing a conclusion similar to

　　that expressed in the first paragraph.

　　（B）The second paragraph provides further

　　elaboration on why an assertion made at the

　　end of the first paragraph proves to be true in

　　most cases.

　　（C）The second paragraph provides additional

　　information in support of a hypothesis stated

　　in the first paragraph.

　　（D）The second paragraph provides an example of a

　　case in which the assumption described in the

　　first paragraph is unwarranted.

　　（E） The second paragraph describes a phenomenon

　　that has the same cause as the phenomenon

　　described in the first paragraph.

　　19.It can be inferred from the passage that the author

　　of the passage would be most likely to agree with

　　which of the following assertions about vigilant

　　behavior？

　　（A） The larger the group of animals， the higher the

　　probability that individuals in the interior of

　　the group will exhibit vigilant behavior.

　　（B） Vigilant behavior exhibited by individuals in

　　small groups is more effective at warding off

　　predators than the same behavior exhibited by

　　individuals in larger groups.

　　（C） Vigilant behavior is easier to analyze in species

　　that are preyed upon by many different

　　predators than in species that are preyed upon

　　by relatively few of them.

　　（D） The term “vigilant，” when used in reference to

　　the behavior of animals， does not refer

　　exclusively to behavior aimed at avoiding

　　predators.

　　（E） The term “vigilant， ” when used in reference to

　　the behavior of animals， usually refers to

　　behavior exhibited by large groups of animals.

　　20.The passage provides information in support of

　　which of the following assertions？

　　（A） The avoidance of predators is more important to

　　an animal's survival than is the quest for food.

　　（B） Vigilant behavior aimed at predators is seldom

　　more beneficial to groups of animals than to

　　individual animals.

　　（C） Different species of animals often develop

　　different strategies for dealing with predators.

　　（D） The size of a group of animals does not

　　necessarily reflect its success in finding food.

　　（E） Similar behavior in different species of animals

　　does not necessarily serve the same purpose.