Answer:
That is administered and controlled
Step-by-step explanation:
A variable is the condition or a product that may vary without the influence of any investigator. Such variables can be found abundantly in our daily lives, ranging from air to sunlight. Controlling such variables ensures the limitation of their influence on the outcome of an experiment. In connection to this experiment, the variables that are controlled are the mineral content in the water, the  amount of bacteria food, the amount of light and the the constant temperature of 20 degrees C.
If not administered or these variables controlled, the experiment would not clearly explain the impact of caffeine on the heart beat of the water fleas as other variables may have influenced it. Thus variables are controlled to study the singular impact of any agent or effect.  
 
        
             
        
        
        
Answer:
its blurry but based on what i see the second one
Explanation:
 
        
             
        
        
        
I believe it is D as it is a better answer than D because of the fact that the statement does not explein the age of her grandmother "old" is just drawing a conclusion off nothing, and it does not say that she does not like her at all , thus it is an incorrect statement . So the answer is D.
        
                    
             
        
        
        
Answer:
<u><em>Some cartilage becomes bone through ossification during childhood development. </em></u>
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Explanation:
You forgot to include options. 
 
        
             
        
        
        
Answer: Liver 
Explanation:
The hepatic portal system of liver connects the capillaries of the gastrointestinal tract to the liver. The nutrient rich blood from the gastrointestinal tract reaches the liver.
The blood that is returned back to the heart is first bought to liver and then it is returned back to the heart.
From the liver after processing the blood goes into heart for further processing.
Hence, the correct answer is option d