Answer:
My best guess would be that the barnacles coexisted with the oysters 100 mya.
Step-by-step explanation:
Since similar oysters were found both in North America and Europe, we know that the oysters were roaming the earth when North America and Europe were once connected. And since barnacle fossils were found in the same layer, we know that they both coexisted 100 mya.
I do not know the options for this question, so this was my best guess.