What condition results in secondary succession?
a. the formation of a tall sand dune on a previously grassy beach
b. a vast glacier in motion forming a u-shaped valley on its wake
c. a volcanic eruption that covers most of what used to be a forest
d. an introduced species that devastates native plants as it feeds

Up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record, about 80 million years ago. but in 1938, a live coelacanth was discovered off the coast of south africa that was compared to the fossil record and found to be the same species what goal of science does this discovery represent