Which statement about UML diagrams is false?

The statement asserting that all object interactions are detailed in class diagrams is not accurate. Class diagrams primarily focus on the static structure of a system, highlighting the classes, their attributes, operations, and relationships with one another. While they can show associations between classes, they do not capture the dynamic interactions or behaviors of objects over time.

In contrast, sequence diagrams specifically focus on the messaging and interactions between objects, detailing how they collaborate in various scenarios based on specific events over time. This allows developers and analysts to see the flow of control and data in a more dynamic context, which is not something class diagrams are designed to represent.

Therefore, the correct choice is the one that highlights that class diagrams do not encompass all object interactions, as this functionality is fulfilled by other types of UML diagrams.