Question

Of all of the alternative hypotheses about how anthropoids first reached south america, scientists are most certain that the ancestors of new world primates rafted across the sea on islands of floating vegetation.

Answer 1

The statement is "False".

Rafting  across the sea on islands of floating vegetation is one somehow possible explanation of how they crossed hundreds of miles of sea water around North America, and their arrival is still a mystery if it comes to certainty for scientists.