Which relationship ensures a sketch edge is made parallel to the x-axis?

The relationship that ensures a sketch edge is made parallel to the x-axis is the horizontal relationship. Applying this relationship to a sketch edge constrains it such that the edge runs parallel to the x-axis, preserving horizontal alignment. This is crucial in design practices as it helps maintain specific orientations and relationships in geometrical drawings, making it easier to control the layout and dimensions of parts being designed.

In a sketch, ensuring edges are precisely parallel or perpendicular to the axes can significantly impact the overall design, affecting things like functionality and manufacturability. By using the horizontal relationship, designers can create stable sketches that adhere to the required planar orientations for accurate modeling.

The other relationships mentioned serve different purposes. For instance, a vertical relationship would constrain edges to be parallel to the y-axis, tangent pertains to curves and lines meeting at one point, and aligned typically relates to ensuring that features are matched in direction but does not specify parallelism to an axis directly.