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
（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
（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
（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
（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.