The following of what? It sounds like there is more than one answer. 
        
                    
             
        
        
        
Answer:
a
. Fish need 10 ml of water purifier to survive.
Explanation:
Fish need 10 ml of water purifier to survive because the data of 10 ml and 20 ml purifier is the same so it is recommended to use 10 ml purifier. First the data was same but by recording next week data, it shows slightly increase in the value of tank 2 while in the last week, both has the same value so we can concluded that by using 10 ml purifier is enough for the fish to survive.
 
        
             
        
        
        
Answer:
i almost can see the thning
Explanation:
  
        
             
        
        
        
Answer:
Open-cast mining
Explanation:
The aftermath of open cast mining are pits (called quarries) on the surface of the earth where the surface soil has been removed/ displaced to access the mineral deposits that are just close or at the surface of the earth. This type of mining results in environmental degradation because they disturb the biodiversity of the ecosystem in which the mining is taking place. Rehabilitation of the area is required after the mining has been exhausted to restore the initial environment.