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