问题详情

Which of the following statements is CORRECT？

A．Aristotle put forward some theories which were not based on observation.

B．The author had seen hedgehogs before he wrote a book about them.

C．It is relatively safe to make some subjective statements about unicorn.

D．Ancient and medieval authors were uncertain of their knowledge about unicorn.

请帮忙给出正确答案和分析，谢谢！