The author of the passage mentions "tiny bones from fish" primarily in order to A. explain why traces of passenger pigeon are rare at Cahokian sites B. support a claim about the wide variety of animal proteins in the Cahokian diet C. provide evidence that confirms a theory about the extinction of the passenger pigeon D. cast doubt on the conclusion reached by the archaeologists who conducted the studies discussed in the passage E. counter an objection to an interpretation of the data obtained from Cahokian sites