Which consistency option ensures that changes appear in order, with possible delays before they are visible?

The consistency option that ensures changes appear in order, with possible delays before they become visible, is consistent prefix. This model allows data updates to be seen in the order they were made, but there may be a lag where not all clients immediately observe those updates.

In a consistent prefix model, if a client reads data after some updates, it will see the updates that occurred before the most recent read but not necessarily all updates in real-time. This means that while the order is preserved, the visibility of the most recent data can be delayed, offering a level of consistency that is suitable for scenarios where the order of operations is crucial but strict real-time visibility is not required.

The other consistency models provide different guarantees: strong consistency ensures immediate visibility of all updates, eventual consistency allows for the case where updates are seen eventually but not in order, and bounded staleness offers a guarantee on how outdated the data can get while still maintaining a consensus on order, but with specific limits on how far behind a read can be from the most recent write.