What feature characterizes mirror-coated lenses?

Mirror-coated lenses are characterized by high reflectivity, which is a result of the reflective coating applied to the surface of the lenses. This coating significantly reduces the amount of light that penetrates through the lens, allowing only a portion of the light to pass. High reflectivity is particularly useful in bright environments, such as when skiing or at the beach, as it helps minimize glare, improving visual comfort.

While the other options present advantages or features that some lenses might have, they do not specifically define mirror-coated lenses. For instance, enhanced UV protection might be present in various types of lenses but is not a defining characteristic of mirror coatings. Similarly, weightlessness does not pertain to the lens coating but rather the materials from which the lenses are made, and better night vision is not a feature associated with mirror coatings, as their reflective nature can actually decrease visibility in low-light conditions.