In which type of changeover does the old and new system operate simultaneously?

The type of changeover where both the old and new systems operate simultaneously is known as parallel changeover. This method allows organizations to compare the outputs of both systems and ensure that the new system is functioning as intended before fully retiring the old system.

By running both systems at the same time, any discrepancies can be identified and corrected without risking disruptions to business operations. This approach is particularly beneficial for critical systems where ensuring continuity and minimizing risk during a transition is vital. It provides a safeguard, as users can revert to the old system if problems arise, which is a significant advantage in terms of risk management during system changes.

The other options refer to different methods of system changeover that do not involve simultaneous operation of both systems. For example, a direct changeover happens when the old system is completely replaced by the new system all at once, which does not allow for simultaneous operation and carries more risk.