Which type of report requires joining classes?

Choosing a report that requires joining classes is critical in scenarios where there is a relational connection between the data entities involved. The correct choice focuses on a list of all child cases showing the work urgency of their parent case.

In this context, child cases contain specific details including their respective urgency statuses while their parent cases aggregate overarching information that might influence that urgency. To generate a report that illustrates child cases alongside their parent case attributes, a join between the child case class and the parent case class is necessary. This relationship allows for a comprehensive view that captures the context and hierarchy, facilitating a clearer understanding of how parent cases impact their child cases in terms of urgency.

Other options like a summary of all cases or a detailed log of user activities do not inherently involve relationships between different classes that require joining. Similarly, a comparison of case resolution times might aggregate data without needing to connect child and parent case classes in a relational database manner. Thus, the specific requirement for joining classes is aptly met in the scenario of parent-child relationship reporting.