Which element use in camera lens?

Which element use in camera lens?

A. Chloride
B. Fluorite
C. Oxide
D. None Of Above

Glass is the most common material used to construct lens elements, due to its good optical properties and resistance to scratching. Other materials are also used, such as quartz glass, fluorite, plastics like acrylic (Plexiglass), and even germanium and meteoritic glass.