Here's a problem to solve: Scientists have discovered fossils of the same organisms in many different parts of the world. These fossils provide evidence that

Among the 4 following options, which is the correct answer?

- A: the continents were once joined together
 
- B: most life-forms that existed in the past are still present today
 
- C: most of Earth's surface was once covered by molten rock
 
- D: rocks have been transformed from one type to another
 