What structure protects the eye from foreign materials?

The correct answer is that the eyelashes play a vital role in protecting the eye from foreign materials. They act as a barrier and can catch dust, debris, and small particles before they enter the eye. Additionally, the presence of eyelashes can trigger a blink response, which further helps to protect the eye by closing it temporarily to keep out objects or irritants.

While the cornea is essential for refracting light and contributing to vision, it does not specifically act as a protective structure against foreign materials. The eyelids also provide protection by closing over the eye, but their primary function is more about protecting the eye from impact and light rather than filtering out particles. The conjunctiva, a membrane that covers part of the eye and lines the eyelids, serves to keep the eye moist and can help protect against pathogens, but it doesn't primarily function to block foreign materials like eyelashes do.