The second one should be your answer, it makes the most sense. at least to me
I believe that starting p2 with the transition "Sadly, by the end...." would work in this case.
If you need more help, comment below and I'd be happy to assist.
Answer:
I like the "Sea turtles have populated Earth's oceans for more than 100 million years." But that's just my opinion
The answer is either A or B. The use of complex sentences can make it seem as if time has slowed down, but it also increases the reader's understanding.
Lmk if this helps!!