The best explanation for why the fossils of the same extinct animals and plants were found in several distant locations is:
B: The continental plates that included South America, Africa, India, Antarctica, and Australia must have been connected 300 million years ago.
This explanation aligns with the theory of plate tectonics, which suggests that these continents were once part of a supercontinent (such as Pangaea) before drifting apart. The presence of similar fossils in different continents supports the idea that these landmasses were once connected, allowing species to inhabit those areas before they separated.