The 3 main regions of the brain are the cerebrum, cerebellum, brainstem.
 
        
             
        
        
        
Answer:
the first one is right ik this i did it give brainliest please
Explanation:
 
        
             
        
        
        
Answer: 
Autotrophs are the organisms which have ability make their own food using various sources of energy. Examples are can green plants and algae such as <em>Spirogyra, Chlorella, Volvox</em> make their food using sunlight carbon dioxide and water.  they are photoautotrophs
Some bacteria are also make their food using chemical energy through oxidation. They are chemoautotrophs.  
 
        
                    
             
        
        
        
Acetylcholine (ACh)
Acetylcholine is an organic chemical that functions in the brain and body of many types of animals as a neurotransmitter.