What defines geometric relationships between sketch entities in SolidWorks?

The correct answer is the option that refers to sketch relations, which are fundamental in defining how different entities in a sketch interact with each other. Sketch relations allow you to impose geometric constraints on entities like lines, arcs, and circles, establishing connections between them that control positioning and behavior while sketching.

For example, if two lines are defined as "parallel," they will always maintain that relationship regardless of adjustments made to one line; this ensures that your design remains consistent. Similarly, other types of sketch relations, such as "coincident," "tangent," or "equal," define specific behaviors which can prevent errors in design and help ensure accuracy when assembling or modifying parts.

While dimensions certainly play a critical role in defining the size and location of sketch entities, they do so in a numeric sense rather than in how those entities relate to each other geometrically. Freeform sketching is focused on creating more complex shapes rather than establishing relationships, and reference geometry serves a different purpose by adding points, lines, or planes that help with the overall design but do not define the relationships between sketch entities directly. Thus, sketch relations are the primary means of defining and maintaining the geometric relationships between sketch entities in SolidWorks.