Approximately 65 million years ago marks the extinction of the dinosaurs, which were the dominant terrestrial vertebrates at the time (and had been for over 100 million years!). What best describes the subsequent emergence of mammals?

The emergence of small mammals in daytime and survival rate due to adaptation with the existing environment was the reason for the subsequent emergence of mammals.

Explanation:

The extinction of dinosaurs made mammals coming out in day light. Paleontologist believe that day time activities of mammals started after the dinosaurs disappeared 65 million years ago at the end of Crustaceous period.

When mammals survived the disaster which finished the dinosaurs. The small mammals like marsupials, insectivores became abundant on earth.

The fur bearing warm blooded mammals eventually evolved in human species.

The eating habits of small mammals left after extinction of dinosaur made them survive where no plant life was left.

a polymer is a chainlike molecule made up of small molecular units. these small molecular units are called monomers. monomers of polymer can be joined together either naturally or synthetically.  

the answer is d. chordata