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 furtherelaboration on why an assertion made at the

end of the first paragraph proves to be true inmost cases.

　（C）The second paragraph provides additionalinformation 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 phenomenonthat 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 t　　the behavior of animals， does not refe　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.