Theory because a theory has to be backed up by several experiments
        
                    
             
        
        
        
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Biosphere- The ecosystem comprimising the entire Earth & the living organisms that inhabit it. Example: Where life occurs on, Earth
Biome- A large naturally occuring community of plants and animals Example: Rainforest, Tundra, Desert, Marine, Grasslands,  etc 
Ecosystem- A community of living organisms  called producers, conumers, decomposers. Example: Plants (Producers) Rabbits (Consumers) Worms (Decomposers)
Community- Interacting group of various species Example: A forest of trees inhabited by animals.
Population- Traits of a group of plants and animals Example: 4 rabbits have broenn fur and 2 have black fur in a group.
Individual- Individual organisms Example:  An otter is a organism
Abiotic examples- Air, soil, sunlight, or water
Biotic examples- A frog, a leaf, or a tree
        
             
        
        
        
Production of energy using water power
Using electricity or energy-saving products, creation of technology to capture sulfur dioxide are the processes that can be taken into account. 
<h3><u>Explanation</u>:</h3>
Acid rain is a very serious issue in the urban areas now a days. Acid rain forms due to the excessive production of gases like sulphur dioxide, nitrogen oxides etc which are beyond the level of absorption by the environment. This gases go up in the atmosphere and they mixes with cloud water to form corresponding sulphuric acid and nitric acid. These acids come along the rain and decrease the pH of the water bodies as well as soil.
If we start using water as the source of our energy production, then we can eliminate the use of coal and other fossil fuels which are chief sources of these gases. 
If we can grow some technology to capture these gases before they are released into the environment, then also there will be less problems. Technologies like alkali bath are not so operative in large scales. 
We can use electricity in boilers and other places where still, fossil fuels are brunt to produce the heat so that sulphur oxides don't come out. 
 
        
                    
             
        
        
        
 <span>Cell theory is really important because it provided, and still provides one of the great unifying theories in biology: one that says in spite of all the vast diversity of organisms, they are are united at a very fundamental level, namely the presence of cells.</span>