What Is One of the Primary Reasons Given for Why

What is one of the primary reasons given for why there are very few fossils from the earliest (pre-Ediacaran fauna) animals?

A) The area covered by land, where early animals lived, was small, therefore there were fewer opportunities for sedimentary rocks to form fossils.
B) The area covered with water was much smaller than present day, therefore there were fewer places for fossilization to occur on the ocean floor.
C) The earliest animals were small and soft-bodied and did not have body parts that could be fossilized easily.
D) The earliest animals were distributed in high oxygen environments and decomposition occurred too rapidly for fossilization to occur.