"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."
This part of the passage gives enough information for choosing option C. Previously only vision was considered as important but now it has been understood that lateral line is as important as vision. Hence there is a bit of dissatisfaction for not grasping the real truth in the first place. Neutrality on the other hand means lack of bias. There is nothing to suggest that the author is neutral towards the structure of the fish schooling maintained through vision.
_________________