Although the schooling of fish is familiar form of animal social behaviour, how the
school is formed and maintained is only beginning to be understood in detail. It had
been thought that each fish maintains its position chiefly by means of vision. Our
work as shown that, as each fish maintains its position, the lateral line, an organ
sensitive to transitory changes in water displacement, is as important as vision. In
each species a fish has a “preferred” distance and dangle from its nearest neighbor.
The ideal separation and bearing, however, are not maintained rigidly. The result is a
probabilistic arrangement that appears like a random aggregation. The tendency of
the fish to remain at the preferred distance and angle, however, serves to maintain
the structure. Each fish, having established its position, uses its eyes and its lateral
lines simultaneously to measure the speed of all the other fish in the school. It then
adjusts its own speed to match a weighted average that emphasizes the contribution
of nearby fish.

1.According to the passage, the structure of a fish school is dependent upon which of
the following.
I. Rigidly formed random aggregations
II. The tendency of each fish to remain at a preferred distance from neighboring
fish
III.Measurement of a weighed average by individual fish
A. II only
B. III only
C. I and II only
D. I and III only
E. II and III only

2.Which of the following best describes the author’s attitude toward the theory that the
structure of fish schools is maintained primarily through vision?
A. Heated opposition
B. Careful neutrality
C. Considered dissatisfaction
D. Cautious approval
E. Unqualified enthusiasm

3. The passage suggests that, after establishing its position in the school formation, an
individual fish will subsequently
A. Maintain its preferred position primarily by visual and auditory means
B. Rigorously avoid changes that would interfere with the overall structure of the
school
C. Make conscious sensory readjustments to its position within the school
D. Make unexpected shifts in position only if threatened by external danger
E. Surrender its ability to make quick, instinctive judgments