What are photochromic lenses known for?

Photochromic lenses are specifically designed to automatically adjust their tint in response to changes in light exposure. When exposed to sunlight, these lenses darken to provide protection from UV rays and glare, making them beneficial for outdoor use. Once indoors, away from UV light, the lenses return to being nearly clear, allowing for unobstructed vision.

This ability to transition between clear and tinted states is the defining characteristic of photochromic lenses, making option B the correct answer. This technology enables wearers to have the versatility of wearing one pair of glasses that can perform well in various lighting conditions, thus eliminating the need for multiple pairs, such as prescription sunglasses. Understanding this feature is essential for consumers looking for practical eyewear solutions.