They mainly target airway epithelial cells
        
             
        
        
        
Im going to go with C only because most dont make sense. 
        
             
        
        
        
The mantle is a layer inside a planetary bodybounded below by a core and above by a crust. Mantles are either made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. The mantle is bounded on the bottom by the planetary core and on top by the crust. In addition to the Earth, the other terrestrial planets, a number of asteroids, and moonshave mantles.
        
             
        
        
        
Answer:
A. Their bodies tend to take in too much water.
Explanation:
Osmoregulation is the maintenance of osmotic concentration inside the body cells and in the extracellular fluid by controlling the amount of water and salts.  Organisms living in water can be divided into two groups: Some are osmoconformers which change the osmolarity of body fluids with respect to the surrounding medium. Some are osmoregulators which do not allow change in internal osmolarity and try to maintain it by various means. 
If as osmoregulator is placed in fresh water environment then their body is hypertonic to their environment. Osmosis will occur which is the movement of water from low solute to high solute concentration. Thus the problems faced by such organisms would be: 
- Entry of excess water
- Loss of body salts to outside.
Adaptations in such organisms would be:
- Body cover such as scales or adipose covers
- They do not drink more water
- Excess water is eliminated as dilute urine
- Special cells called ionocytes or chloride cells help in active uptake of sodium ions and chloride ions.