I would have to say (D.) if it's been 150 years.
        
             
        
        
        
Answer:

Explanation:
In a chemical reaction, the <u>produc</u>ts are <u>produc</u>ed. The <em>react</em>ants are the substances that <em>react.</em>
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In a chemical reaction equation (with the arrow pointing right) the reactants are on the left and the products on the right. 
The reactants enter and the products come out. 
So, the statement given - products enter a reaction and reactants come out - is false and it is actually the other way around. 
 
        
             
        
        
        
They can slow their heartbeat down
        
                    
             
        
        
        
1) occluding junctions
2) anchoring junctions
3) communicating junctions
Occluding junctions do not totally seal the space between cells and the resulting permeability varies greatly.  I would say anchoring junctions are most likely with one of the other 2 junctions being least permeable.