355.When youre performing active database duplication, a backup of what kind is required?
A. A current RMAN backup-set backup is required.
B. No backup is required.
C. An RMAN image backup is required.
D. A manual backup is required.
E. A "duplicate" preparatory backup is required.
Answer: B
答案解析：
可以直接复制一个活动的数据库而不需要任何备份。