What characteristic of clear glass is most notable?

The characteristic of clear glass that stands out the most is its maximum visible light transmittance. Clear glass is specifically designed to allow a high percentage of visible light to pass through it, making it ideal for windows and other applications where natural light is desired. This property is crucial in architectural design to enhance the illumination of interior spaces without significantly altering the appearance or color of the light.

While other options do highlight important attributes of glass, they do not define clear glass to the same extent as its light transmittance. For instance, impact resistance can vary significantly depending on the type of glass, while insulation against sound is generally not a primary characteristic of clear glass, often requiring specialized acoustic materials. Reflective qualities are also not a defining feature of clear glass, which is typically known for its transparency rather than its ability to reflect light.