Why are drift nets a problem?

a. too expensive to be practical
b. not big enough to catch many fish
c. they are too big and hard to manage
d. they can accidently catch dolphins and turtles

Drift nets is a net for herring which is kept upright by its weights and it floats at the top. So basically it is hanging vertically. Thus, the problem with drift net is that it can catch any fish or organism that pass through it including dolphins and turtles. Therefore, the answer is D. 

I’m confused ///: : : :