单项选择题

A.A full database backup should be performed once daily. During business hour, a transaction log backup should be performed every two hours. 
B.A full database backup should be performed once daily 
C.A full database backup should be performed once daily. During business hours, a differential backup should be performed every two hours 
D.Perform a full database backup should be performed once every week. A differential backup should be performed once daily. During business hours a transaction log backup should be performed every two hours.