Which characteristic describes how light travels?

Light travels in straight lines primarily due to its wave nature and the principle of linear propagation. In a vacuum or uniform medium, light travels in straight paths because it follows the laws of reflection and refraction, which are based on straight-line motion until it encounters an obstacle or a medium change. This straight-line propagation is fundamental to understanding how we perceive light and forms the basis for many optical principles, such as how lenses function and how shadows are cast. This characteristic is why we draw light rays as straight lines in diagrams and why we can predict how light will behave in various situations, such as when it interacts with mirrors or refractive surfaces.