A person who specializes in the study of animals is called a zoologist. Zoologists who study certain kinds of animals have their own names.
Option C, animals moved from the sea to the land is the right answer.
The Paleozoic Era in the history of the earth was a time of major change on Earth. This was the period that ran about 542 to 251 million years ago. The period commenced with the split of a single super-continent and the development of another. Plants grew extensively. Moreover, the primary vertebral animals conquered the land.
Recombinant DNA or rDNA is the general term given to the process of taking a piece of a DNA and merging it with another strand of DNA. The combination of two or more different strands of DNA allows scientists to be able to produce a new and different strand of DNA. Combination of the DNAs of two different organisms is one of themost common recombinant process. The combination of these strands of DNA will give way to the creation of the cure of a lot of genetic diseases in the future like cell anemia, cystic fibrosis and the likes.