Scientists are constantly learning more and more about fossils because
a. fossilization is common process, so there are many fossil samples for nearly all species that have existed on earth.
b. new fossils are continually being discovered.
c. the fossil record is complete, covering every species that has lived on earth.
d. fossils provide different information at a different times of day and in different locations.

B. New fossils are continually being discovered.

Explanation:

Fossils are the dead hard remains of plants, animals and other primitive organisms that existed on earth history.

The scientists are concerned about fossils because new fossils are continually discovered. After the excavation process the identification of the class, order, genus and species becomes the priority of the scientists. The scientists becomes curious to know the relatedness of the found fossils to the primitive known and present day organisms.