Answer:
Proterozoic Eon
Explanation:
The Proterozoic Eon is the most appropriate eon to indicate the geological age of this rock unit. This is because this rock presents fossils of the first multicellular and soft-bodied marine organisms and it was in the Eon Proterozoic that the first single-celled living organisms appeared.
The Proterozoic eon, as already mentioned above, is characterized by being the period of the land where the first multicellular marine organisms appeared. This period is divided into three ages: Paleoproterozoic Era (where eukaryotic beings arose), Mesoproterozoic Era and Neoproterozoic Era (where the first multicellular marine organisms arose).
