In which of the following cases, cited as an example by a WP29 guidance, would...

According to the WP29 guidance on DPIA1, conducting a single DPIA to address multiple processing operations is allowed when the following conditions are met:

The processing operations present similar high risks, which would result in very similar mitigating measures;

The DPIA is reviewed and updated regularly to take into account any changes or new risks;

The DPIA is complemented by ad hoc assessments where necessary to address more specific issues.

The WP29 guidance cites the example of a railway operator who plans to evaluate the same video surveillance in all the train stations of his company as a case where a single DPIA would be sufficient, provided that the above conditions are met2. The other options do not meet these conditions, as they involve different types of processing operations, different purposes, different data subjects, or different technologies. References:

WP29 guidance on DPIA

WP29 guidance on DPIA, page 16