Optical fiber is a kind of () A. inorganic nonmetallic material B. metal material C. organic polymer material D. composite material.

A, optical fiber is made of silicon dioxide, which belongs to a new inorganic nonmetallic material. Traditional inorganic nonmetallic materials and new inorganic nonmetallic materials are collectively called inorganic nonmetallic materials, so A is correct;

B, metal materials include metal simple substance and alloy, and the material for making optical fiber is silicon dioxide, so B is wrong;

C, optical fiber belongs to a new inorganic nonmetallic material, and its raw material silica is inorganic, so C is wrong;

D, composite material is a kind of material with special properties obtained by combining a variety of materials together. Optical fiber is made of pure Shi Ying crystal, which is not a composite material, so D is wrong;

So choose: a.