Choose the appropriate word for the blank space to complete the sentence of the following passage:But he realized that light entering the eye was only the first step in seeing. He built on the work of Greck physician Galen who had 2. ______ a detailed description of the eye and the optic pathways. Today the oldest-known drawing of the nervous system is from Ibn al-Haytham's Book of Optics, in which the eyes and optic nerves are illustrated.

A concealed

B predicted

C provided