What is the purpose of the third eyelid in rabbits?

The third eyelid, also known as the nictitating membrane, plays a crucial role in protecting the cornea of rabbits. This translucent membrane can quickly sweep across the eye, shielding it from potential irritants like dust, debris, and other foreign particles. In environments where dust storms or similar conditions can occur, the third eyelid serves as an important barrier, helping to maintain eye health by preventing damage that could be caused by gritty substances.

It's important to understand that while other options mention enhancement of vision, protection from predators, and filtering sunlight, the primary and more immediate function of the third eyelid lies in safeguarding the cornea from environmental threats, ensuring that rabbits can continue to see clearly without damage to their eyes.