Which constraint causes two or more line segments to lie on the same line?

The collinear constraint is specifically designed to ensure that two or more line segments align perfectly along the same line. When this constraint is applied, it forces the selected entities to maintain a straight line relationship regardless of their individual positions or lengths. This means that if one segment is moved or resized, the others will automatically adjust to stay on the same line, maintaining their collinearity.

On the other hand, the coincident constraint relates to the geometric relationship of points, ensuring that two points occupy the same position in space. The parallel constraint maintains a fixed angle between two lines, ensuring that they will never cross but do not necessarily require that they lie on the same line. The horizontal constraint enforces a horizontal orientation on a line but does not ensure that multiple lines will occupy the same linear path. Thus, collinear is the precise term that describes the condition of multiple line segments lying along the same straight path.