What example illustrates a multi-link dwelling?

The correct answer demonstrates the concept of a multi-link dwelling by illustrating how residential units can be physically connected through shared structural walls. A multi-link dwelling typically refers to various forms of housing that are connected to one another, which can often include features like shared walls or common areas.

In this case, a house where the primary wall is attached implies that it shares a wall with another dwelling. This structural connection is a fundamental characteristic of multi-link dwellings, as it allows for efficient use of space and resources, and it often promotes a sense of community among residents.

While the other options may contain elements of shared living (like row houses or condos), they either do not specifically emphasize the connection through shared walls in the same way or describe types of arrangements that are more general and less distinct from single-family homes. Thus, the choice that refers to a house where the primary wall is attached best exemplifies the concept of a multi-link dwelling.