Answer:
genetic trait=eye color (a)
environmentally influenced trait=the language you speak (b).
Although the dolphin lives in the sea, it is not a fish - it's a mammal.
It makes the most sense if you read it aloud.
Answer:
Paleontologists didn't have the technology in that time to get a good estimation on the events. Back then, they had to rely on natural sources "markers" that made the estimations. Those estimations weren't accurate. Today's measures are accurate.
Extinction or population loss
