Thanks for your question! The question is asking us for a statement that helps explain most the biologists’ findings. Those findings are twofold: that the p-plankton population has been dropping and the population of certain species of fish is also decreasing. (D) is wrong because it only explains one of the two parts. It gives us insight onto why the fish population is decreasing but doesn’t tell us about why the P-plankton population would be decreasing. (B), on the other hand, gives a reason that both populations might be decreasing, and so is a better answer. Hope this helps! Feel free to ask any further questions that you might have.
ashwinidFebruary 8, 2020
Thank you Shunhe. Very clear explanation. I understand the reason for the correct answer choice now.
HannahAugust 22, 2022
Do we need to resolve the part that discusses why the plankton is dropping? If we have the link that establishes the connection between the XYZ fish dropping because of starvation due to increased plankton deaths shouldn't this be sufficient to establish that "the decline in plankton population is extreme enough for the decline in the fish population to make sense?" Is it necessary to understand what is causing the plankton deaths?
Emil-KunkinAugust 29, 2022
I don't think we necessarily need to show why the plankton are being killed, but given that we're being asked to explain a weird scenario, it's certainly good that B does explain why.
