Answer:
c. Pyridostigmine binds to the acetylcholinesterase active site and prevents sarin from binding to and modifying the enzyme active site.
Explanation:
Sarin is a toxic compound which inhibits acetylcholinesterase enzyme. This enzyme degrades the neurotransmitter acetylcholine after the required muscle cell stimulation. In absence of its activity, acetylcholine is not degraded and the muscle cells are stimulated uncontrollably. The muscles are not able to relax which ultimately proves fatal for the victim.
Pyridostigmine is also an acetylcholinesterase inhibitor like Sarin. However its period of inhibition is short compared to organophosphorus inhibitors like sarin. It competes with sarin and replaces it in the active site of acetylcholinesterase. The enzyme is still inhibited but for a shorter time as compared to inhibition by Sarin. Hence after sometime, it becomes functional again and resumes its normal activity. Acetycholine starts getting degraded relaxing the muscles. 
 
        
             
        
        
        
Answer; 
a.) the most common kind of cell division 
c.)same number of chromosomes in each daughter cell as in the parent cell.
Explanation; 
-Mitosis is a type of cell division which takes place ins the body cells or the somatic body cells, where the parent cell divides to give two daughter cells that have the same number of chromosomes as the parent. Thus, if the parent cell will be diploid (2n) then the daughter cells will also be diploid (two sets of each chromosome).
-This type of cell division plays an important part in the development of embryos, and it is important for the growth and development of human bodies as well.
 
        
             
        
        
        
Answer b is the best example
        
                    
             
        
        
        
Answer:
<em>Open </em><em>circulatory </em><em>system</em><em> </em><em>is </em><em>the </em><em>system </em><em>that</em><em> </em><em>is </em><em>primarily</em><em> </em><em>found </em><em>in </em><em>invertebrates.</em>
 
        
             
        
        
        
The answer is low light intensity! I hope this helps!