When considering the option to migrate from an on-premises environment to a hosted cloud service, an organization should weigh the risks of allowing external entities to access the cloud data for…

'Not securing the data in the legacy environment' is a general security failure, not a specific alternative for facilitating external collaboration compared to cloud.

'Disclosing the data publicly' represents a worst-case scenario or an uncontrolled leak, not a controlled collaborative effort comparable to the cloud scenario described.

'Inviting external personnel into the legacy workspace' is one method of collaboration, but it focuses on physical access to the workspace rather than the data's movement or remote digital access for collaboration, which is a more direct parallel to cloud-based external access.

The question is asking for a comparative risk assessment. If the organization is not migrating to the cloud, the alternative for 'external entities to access data for collaborative purposes' would be to achieve that collaboration by sending data out of the on-premises (legacy) environment. Thus, the risks of cloud-based external access should be weighed against the risks inherent in traditional, non-cloud methods of external data sharing and collaboration.