Answer:
This question is not well placed. It should be " a relationship between two organisms in which both benefit is called". 
The answer is SYMBIOSIS
Explanation:
Living organisms tend to interact with one another in their natural environment. This interaction are of different types depending on the effect on the involved organisms. One of those interactions is SYMBIOSIS. Symbiosis is a relationship between two organisms in which both of the organisms benefit from one another. 
An example is the relationship between the "CATTLE AND EGRET". The cattle provides food for the egret when they feed on the insect parasites on their body while the egret helps the cow get rid of detrimental parasites. 
 
        
             
        
        
        
Water reacting with nitrogen gas i think, since it doesn’t actually react
        
                    
             
        
        
        
Answer:
0.153
Explanation:
We know the up-thrust on the fish, U = weight of water displaced = weight of fish + weight of air in air sacs.
So ρVg = ρ'V'g + ρ'V"g where ρ = density of water = 1 g/cm³, V = volume of water displaced, g = acceleration due to gravity, ρ'= density of fish = 1.18 g/cm³, V' = initial volume of fish, ρ"= density of air = 0.0012 g/cm³ and V" = volume of expanded air sac. 
ρVg = ρ'V'g + ρ"V"g 
ρV = ρ'V'g + ρ"V"
Its new body volume = volume of water displaced, V = V' + V"
ρ(V' + V") = ρ'V' + ρ"V"
ρV' + ρV" = ρ'V' + ρ"V"
ρV' - ρ"V'  = ρ'V" - ρV"
(ρ - ρ")V'  = (ρ' - ρ)V"
V'/V" = (ρ - ρ")/(ρ' - ρ) 
= (1 g/cm³ - 0.0012 g/cm³)/(1.18 g/cm³ - 1 g/cm³) 
= (0.9988 g/cm³ ÷ 0.18 g/cm³) 
V'/V" = 5.55
Since V = V' + V"
V' = V - V" 
(V - V")/V" = 5.55
V/V" - V"/V" = 5.55
V/V" - 1 = 5.55
V/V" = 5.55 + 1
V/V" = 6.55
V"/V = 1/6.55 
V"/V = 0.153
So, the fish must inflate its air sacs to 0.153 of its expanded body volume
 
        
             
        
        
        
B. the same number of chromosomes as the parent cell. - as a result of mitosis.
        
                    
             
        
        
        
Retina receives lights and transfers it to the Optic Nerve