C. The brain sends messages to the spinal cord
        
             
        
        
        
Answer:
B
Explanation:
The structure of the mitochondrion is key to the process of aerobic (in the presence of oxygen) cellular respiration, especially the Krebs cycle and electron transport.
 
        
                    
             
        
        
        
B . Excessive commercial fishing 
Reason: the other options are good things this is the only bad thing
        
             
        
        
        
Electromagnetic radiation is a type of energy that is commonly known as light. Generally speaking, we say that light travels in waves, and all electromagnetic radiation travels at the same speed which is about 3.0 * 108<span>meters per second im pretty sure through a vacuum. We call this the speed of light nothing can move faster than the speed of light according to electromagnetic wave lengths.  hope i could help if not please explain that way i can :)</span>
        
             
        
        
        
Answer:
Helium and carbon dioxide