The best answer in my opinion is the third choice.
I’m not exactly 100% sure but I think it’s D
'Finally' is the answer the others don't make sense if you try to read them with the rest of the sentence.
The last one is not true. Only the second statement mentions how fragile the environment is that coral reefs exist in.The first statement focuses on erosion and pollution as causing the reefs to die.
C...
Hope I helped!!
Brainliest is always appreciated! =)