The lens helps the eye to focus on images.
"The Lens. The lens is composed of transparent, flexible tissue and is located directly behind the iris and the pupil. It is the second part of your eye, after the cornea, that helps to focus light and images on your retina."
C should be the answer because in that example he is not prepared nor is his flexible easily flexible by him being out at the movies on a weekend that he is on call. It shows the importance of needing to be flexible and easily adaptable in case of emergency.
