The correct answer is that the shells of clams and other mollusks dissolve when the pH becomes more acidic.
This is because the shells of clams and other mollusks are made of calcium carbonate that is dissolved in acidic conditions. The pH  needs to be low to dissolve calcium carbonate into it. It takes few days to dissolve the shell completely. 
 
        
                    
             
        
        
        
Answer: The correct answer for the fill in the blank is High.
Hypotonic solution is the one, which contains less concentration of solute (like salt)  as compared to the solvent (water).
In other words, in a hypotonic solution, the concentration of solvent is higher than the concentration of solutes.
Thus, the relative concentration of water ( which is a solvent) in a hypotonic solution is high.
 
        
                    
             
        
        
        
Answer:
A.
Explanation:
survivors may develop huge psychological problems due to the remaining options in the question
 
        
             
        
        
        
Answer:
Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product.