单选题 As we know, blood types A and B cannot receive AB, but AB may receive A or B. Type O can give to any other group; hence it is often called the ______ do- nor.
【正确答案】 B
【答案解析】universal donor万能献血者；universal普遍的，一般的；common常见的，平常的；general普通的，一般的；popular流行的，受欢迎的。