Which of the following is a phantom line in the alphabet of lines?

A phantom line is represented by a specific style that typically consists of alternating long and short dashes. This unique pattern is used extensively in technical drawings and engineering for various purposes, such as indicating the outlines of an object that is not currently visible or showing movement or paths of motion.

Choosing a dashed line reflects an understanding of how different line types serve distinct roles in technical illustrations. The other line types, while important in their own rights, are utilized differently. A solid line typically represents edges or outlines that are visible; a hidden line denotes edges that are not visible from the current viewpoint; and a center line is used to indicate symmetry or positioning in relation to other elements. None of these options align with the characteristics or applications of a phantom line, which is specifically defined by its dash and dot pattern.