For Many Years,scientists Believed That Almost All Animal Lineages Burst

For many years,scientists believed that almost all animal lineages burst into being during the Cambrian era (just after the end of the Precambrian super eon) .However,there have been many recent findings of animal-like fossils and "trace fossils" (fossils of an animal-like organisms movement) from the late Precambrian.Which of the following best explains why it took so long to realize there was animal-like life in the Precambrian?

A) Animals from the late Precambrian had soft bodies.
B) There were many hard-shelled animals in the Cambrian.
C) The global climate was such that there was poor fossilization in the Precambrian.
D) There were very few animals during this period.