Answer :
I believe that the answer is b. From the picture I can see a little bit of water so, It wouldn't be in a Marine environment. It looks like it was formed on a riverbed. Erosion probably caused the layers to form on the riverbed.
the answer is a i just took the test and a is correct the 1st question answer is What does an unconformity in a sequence of rock layers reveal about geologic history?
A.
A rock layer must have turned upside down.
B.
A layer of rock might have eroded.
the answer is b