Question on Biodiversity

[dongzzhong]

I am new to this forum and I couldn't find another biology related forum, so I was wondering if anyone could provide me with some help. The following is a question and the correct anwser is (E), however I need to explain why the other choices are wrong. Below is my question followed by my explanation. I am a little confused by the question so please advise me on any errors. Thanks you very much.
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A one-hectare pond is sampled in early September.
The sample yields 1 small catfish as well as 17
benthic invertebrates that represent l0 species.
16. If the pond is resampled a year later, which of the
following would best indicate that the pond had
been adversely affected by adjacent development?
(A) An uncommon species has become more
numerous.
(B) An increase in low-tolerance species has
occurred.
(C) A decrease in high-tolerance species has
occurred.
(D) Phylogenetic diversity has increased.
(E) The biodiversity of the pond has decreased.
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My explanation:
16. E) is the correct answer.
A) This could be the simply the result of natural evolution processes.
B) The low-tolerance species may have gained special adaptation over the year.
C) The high-tolerance species may have experience a natural change that result in its demise.
D) Phylogenetic diversity is a measure of biodiversity, so its increase could not result from such development.
Thanks!!!

[jwalin]

the catfish will eat the benthic invertibrates so the biodiversity will decrease the rest of the option u can eliminate very easily... Just think about it

[JackBean]

jwalin: what reasoning is that?

dong: If there was any ADVERSE effect, then the biodiversity simply MUST decrease. The others can be eliminated relatively simply.