by the type of item by the size of the item by the person who located the item by the soil layer where the item was found
I gave my students this multiple choice question: At an archaeological dig site, scientists, volunteers, and students collect items used by people living hundreds of years ago. To determine the history of the different people who may have lived at the site, which is the best method to classify the recovered items?

Only one answer is correct among these 4 choices:
- by the type of item
- by the size of the item
- by the person who located the item
- by the soil layer where the item was found

Could you tell me which one is correct?

by the soil layer where the item was found