Which type of conversion involves introducing a new system while the old system remains operational for a period of time?

The appropriate choice for this question is parallel conversion. This method allows both the old system and the new system to operate simultaneously for a specified period of time. The primary advantage of this approach is that it enables the organization to verify the new system's performance and functions while still having access to the old system as a backup. This helps in mitigating risk, as users can compare outputs and ensure that the new system meets all required specifications before fully transitioning.

This approach also provides a safety net; if issues arise with the new system, users can revert to the old system without significant disruption to the organization’s operations. Therefore, it serves as a reliable transition strategy for implementing new technology while maintaining business continuity.