Which of the following statement is true according to the third paragraph
A.In the North Sea, trawling one or more times in a year is beneficial for fish stocks.
B.It is universal that trawling can increase fish stocks.
C.The area in which shifting sands and gravels are stirred up by strong tidal currents is beneficial for fish stocks.
D.Smaller critters help to nurture more marine life, because they are the main food for the fish.