What does the SCN represent?（）
- AThe system change number, which is a point in time relative to transactions within a given database.
- BA number that represents time. Thus, at 1300 hours, the SCN is the same on all databases.
- CThe security change number, which represents the security code that is needed to access any database structure.
- DA conversion factor that converts internal database time to external clock time.
- EUTC time in the database, providing a standardized way of tracking time in Oracle.&e