Which of the following is not a valid class relation in a class diagram?

In a class diagram, valid class relations include composition, aggregation, and association, which are foundational concepts in object-oriented design that describe how classes interact with one another.

Composition is a strong type of association that implies ownership, where one class (the whole) contains instances of another class (the parts), and the lifecycle of the part is tied to the whole. If the whole is destroyed, the parts also cease to exist.

Aggregation, while also a type of association, represents a "whole-part" relationship with less stringent ownership. In this relationship, the parts can exist independently of the whole, meaning that if the whole is destroyed, the parts remain.

Association refers to a more general relationship between two classes, indicating that they are connected but without the stronger ties seen in composition or aggregation. It encompasses various degrees of connection and can involve referencing or using instances of one class within another.

Merge, on the other hand, is not a standard class relation in UML class diagrams. It pertains more to scenarios in modeling, particularly in the context of state machines or activity diagrams, where it represents a way to combine multiple paths or transitions into a single one. Thus, it does not fit into the category of valid class relations that define how classes interact in a