0/3 then 2/3, have to lock in CondR prep

I am a bit confused about why the assassination failure isn't /AAF, since it is the negated sufficient.

I did write /A -> /DS, which I can see becomes DS -> A (which I thought didn't make sense realistically), but was stumped how after it's AAF and not /AAF

I was hesitating on B because I thought we had to prove the connection of the plankton eating the fish. Though I did think D didn't add much🥲

Passage one was so challenging, or maybe science in general is hard🥲

Is A like saying AA-> reduct in M -> reduct in CD? If so, I thought you should not assume -X -> -Y

I don't really understand how the negation works in answer choice D