Which of the following accurately describes the behavior of a block once it has been modified?

The correct choice indicates that modifications made to a block only influence new instances of that block. This aligns with how OutSystems handles component versions and changes in modules. When a block is modified, any instances that were created before the modification will retain the original behavior and structure, as they were instantiated based on the pre-modification version. Only when new instances of the block are created after the modification will they incorporate the changes made.

This ensures that existing applications remain stable and that any modifications do not inadvertently disrupt functionality—providing developers the flexibility to make updates without breaking existing implementations. This benefits workflows where several versions of a block might be utilized simultaneously across different parts of an application, allowing for smoother transitions during development.

In contrast, other options imply that existing instances or referenced entities are automatically altered or that manual intervention is required to refresh old instances, which is not how the OutSystems platform operates in terms of instance management and block modifications.