Answer:
lack of oxygen
Explanation:
Just like us humans, plants also need oxygen to live
 
        
                    
             
        
        
        
The deep ocean vessels habe very thick windows and walls because the at very depth ocean the pressure is very high so the vessels should have very thick windows and walls to withstand the great pressure that is applied on the vessel. this also to insure the safety of the people inside it.
        
             
        
        
        
I think the respiratory system and circulatory system