Which of the following statements best reflect Darwin's reasoning for this prediction? Select all correct answers.
a) All present-day species evolved from preexisting species. There must have been transitional forms with features of both the present-day species and the preexisting species from which they evolved, which could be found in fossils.
b) Throughout life's history, the evolution of new, major groups of organisms occurred over long periods of time and in many steps. Therefore, there are probably fossils like transitional fossils that show some of these steps.
c) Individual organisms can change into new species through transitional forms. An example would be an individual fish becoming a new land animal.
d) Therefore, fossils of transitional forms probably exist.
e) The fossils of every species that ever existed will eventually be discovered, and it is likely that some transitional fossils will be among them.