When the controller's necessity is the legal basis for processing, what must be provided to the data subjects?

When the controller's necessity is the legal basis for processing, it is critical to provide data subjects with the information regarding the controller's legitimate interest. This is rooted in the principle of transparency, which is a key aspect of data protection laws, including the General Data Protection Regulation (GDPR).

When a controller relies on legitimate interests, it must clearly communicate to data subjects what those interests are and how their personal data will be used to achieve those interests. This helps data subjects to understand the purpose of the data processing and gives them insight into how it may affect their own privacy rights. It also allows individuals to assess whether they have any objections to the processing of their personal data based on these interests, supporting their right to make informed decisions regarding their personal information.

The other options, while relevant to data processing and privacy rights, do not directly address the necessity legal basis or the specific obligations that arise from it, thus making them less pertinent in this context.