First of all, how I would map this out and take notes while reading would be something like this:

2 theories why schooling occurs--both assume protection from predators
Theory A--predator's chance of finding a fish in school<finding one if dispersed
Theory B--"Confusion effect"- 2 explanations
---1) pred cannot decide
---2) sensory confusion

Notes like these will help you keep track of where everything is and help you find specific information when you need it to answer a question.

Question 1 asks about theory B, so we know its in paragraph 3.
A) is incorrect, because theory B says their are values beyond the group
B) seems promising, as sensory confusion from the movement is an explanation for the confusion effect
C) it incorrect, nowhere does it say that predators cannot detect entire schools
D) There is also nothing about hiding in theory B
E) also out of scope, because the passage says nothing about the groups dispersing
Thus, B is the answer

Question 2 asks about both theory A and B, so it it likely more dispersed throughout the passage or in paragraph one, which discusses both. This question also asks for something that is true for BOTH theories, so if it is not true for one, we can eliminate the whole answer
A) is wrong, because they are not hiding from predators, especially not in theory B.
B) this is promising, both theories do explain how forming schools protects from predators
C) there is no mention of other protective behaviors, so eliminate
D) nothing about small fish specifically, so eliminate
E) again, there is nothing about small and large, so eliminate
Thus, B is our answer

Question 3 asks about the confusion effect, so we know to look in paragraph 3
A) out of scope there is no mention of a specific number of meters
B) although this might be a logical leap in the real world, there is no mention of the fish's position in the school, so eliminate it
C)there is no mention of the size of the school, so eliminate
D) The fourth and fifth sentence in the 3rd paragraph explain why this is true
E) no mention of size, so eliminate
D is our answer

Question 4 is a general question, so there is no specific part to go back to
A) seems to be right, the author does discuss different theories
B) they are not techniques
C) defending is too strong a word
D) he does not refute anything
E) no new evidence is revealed
Thus, the answer is A
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Hello ,

Yes the answers are straight forward but can some one help me in understanding the flow for theory A in the passage.

Proponents of theory A dispute the assumption that a school of thousands of fish is highly visible. Experiments have shown that any fish can be seen, even in very clear water, only within a sphere of 200 meters in diameter. When fish are in a compact group, the spheres of visibility overlap. Thus the chance of a predator finding the school is only slightly greater than the chance of the predator finding a single fish swimming alone.

People in favor of theory A first dispute that School is highly visible and then they conclude that chance predator finding the school is slightly greater than finding individual fish.
To me the two statements seems to oppose rather than support .

Where am I going wrong ?

4. The author is primarily concerned with
(A) discussing different theories--yes theory A and B
(B) analyzing different techniques--only one technique is mentioned that is "schooling"
(C) defending two hypotheses--author is not defending anything
(D) refuting established beliefs--he is not refuting any belief
(E) revealing new evidence---no new evidence is outlined rather exisiting theory is discussed..

Hope it helped....