Answer:
A. Integumentary system 
Explanation:
The integumentary system consists of the skin,hair and nail. This system consists of the largest organ in the body. The skin helps in protection against pathogens by shielding the internal body system from external objects.
The skin also helps in Vitamin D production through sunlight.
It also helps to prevent dehydration through regulation of water loss.
 
        
             
        
        
        
Answer: C. there is more silicon than calcium at the surface of the earth
Explanation:
 
        
             
        
        
        
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. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by- products and ATP is energy that is transformed from the process.
Explanation:
 
        
             
        
        
        
The error is that four haploid daughter cells are made so it needs to be 4N, because there should be 4 instead of 2