单选题

　　[阅读理解]“Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed，” Allen said. “We have a lot of work to do to rule out （排除……的可能性） possible non-biological explanations. It is more likely that a chemical process， without biology， can explain these results.”

　　What can be inferred from what Allen said？

　　A.Scientists have different arguments over whether there is life on Titan.

　　B.Scientists all agree that there is life on Titan.

　　C.Scientists all suggest that a biological explanation is reasonable.

　　D.Scientists all agree that a non-biological chemical reaction is a possible explanation.