Answer:
A. The specific functional role of an organism
Explanation:
A habitat is the general place where an organism lives and a niche is the range of physical and biological conditions in which a species lives and the way the species obtain what it needs to survive and reproduce.
Well, MOST pathogenic bacteria is harmless, but SOME could cause death, like tuberculosis, but just in case you would want to mark the answer as, "True".
I hope I helped! =D
Paleontology is the study of the history of life on earth as based on fossils.