UML class diagram - show class relationships

Question: I want to look at the relationships between the classes in my software application. What UML diagram should I use?

UML Class diagrams are very good for showing the static relationships between classes, such as inheritance and aggregation, one to many relationships, and many other class relationship details.

Interaction diagrams (sequence diagrams and collaboration diagrams) are good for showing the dynamic collaboration between classes/objects during process within an application, such as the collaboration required to fulfill the needs of a use case.