Fossil evidence can be used to determine the degree to which different organisms are related. The relatedness of organisms can also be determined by examining A. internal and external anatomical features of the organisms.
B. ancestors that the organisms share in common.
C. chemical processes that occur within the organisms.
D. all of these

Crinoids, also known as sea lilies, appear to be sea plants but are not plants at all. crinoids are an echinoderm species which uses anchoring structures called holdfasts to attach themselves to the sea floor. crinoids were most abundant in pennsylvania during the mississippian period, which ranged from 375 to 320 million years ago. fossils of the crinoids shows that during most of this time pennsylvania was that provided favorable conditions for crinoid growth. a) glacial terrain b) a dry and sandy plain c) mostly mountain ranges d) covered by warm, shallow seas