The three parts of the cell theory are as follows: (1) All living things are made up of cells, (2) Cells are the smallest units (or most basic building blocks) of life, and (3) All cells come from preexisting cells through the process of cell division.
        
                    
             
        
        
        
Answer:
The answer is various general sensory receptors 
Explanation:
All of the listed responses are correct. All structures sensitive to stimulus arising outside the body.