Given the task definition and input, reply with output. You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).

Paragraph: Lower rock layers were laid down earlier, so they are assumed to contain older fossils.
 Question: Sean digs in the dirt and finds rocks that are buried very shallowly. Given how deep they were, Sean can assume that these rocks are 
 Choices: A)younger 
B)older
younger