Light is converted into nerve impulses in the retina apex

Retina

The retina is the part of the eye which converts light into electrical impulses with its photoreceptor cells (rods and cones) to the brain. Vision is achieved when light enters the pupil, focused by the lens, and converted into signals in the retina.  

                                                        water

a colorless, transparent, odorless, tasteless liquid that forms the seas, lakes, rivers, and rain and is the basis of the fluids of living organisms.

                                                        halon  

any of a number of unreactive gaseous compounds of carbon with bromine and other halogens, used in fire extinguishers, but now known to damage the ozone layer.

                                                  dry chemical

extinguishing agent used on class a, class b, and class c fires.

                                                  carbon dioxide

a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. it is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.