Why do some scientist now think that some early american may have arrived in the americas via boat

Most archaeologists think the first Americans arrived by boat. The density of early coastal sites here "is unprecedented in North America," says archaeologist ... Some archaeologists argue that the first Americans might have entered via the "This is the biggest scientific effort to move us down the road to ...

New evidence has challenged the idea that all early Americans arrived via Beringia.

Explanation:

Most archaeologists believe that Beringia would be partially submerged. The people who came to the Americans would have to had taken a boat and quickly moved down the pacific coast, reaching Chile. There's no absolute proof, and there are some variations of this theory, but generally, they all contest the idea of early Americans arriving via Beringia.

i would say your answer is a)

sorry if im wrong