The Central Nervous System includes: Everything except the brain and spinal cord

The spinal cord and sensory neurons

The brain and spinal cord

The brain, spinal cord, and sensory neurons

The brain and spinal cord

Explanation:

The central nervous system is made up of the brain and the spinal cord. The brain plays a very important role in the body as it's used in controlling most of the bodily functions, such as movements, speech, awareness, memory etc.

The spinal cord is vital as it helps in sending signals from the brain to the rest of the body and controls musculoskeletal reflexes.

                                                        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.

frequency is the answer