For me, the biggest indicator that I used to determine why D was incorrect was that part of their findings were that the two phenomena were connected. D explains why the fish population went down, but it doesn't say why the Plankton population went down. For B, we are told why the plankton population has decreased. We then could make the assumption that the fish population went down because of that part alone, but we are also given another piece of info that describes why the fish population went down.

I am interested in joining! I am taking the September LSAT and would love to study with a group. I tried clicking the links to the discord servers, but I receive a message that says the invite is invalid.