In making an experiment their are two types of variable that should be consider, one is the dependent variable and the other one is the independent variables. I the question that dependent variable would be the result or the effect of the gender of mice and the independent is the ways in determining it. So the variables should be fair if you want your result to have no bias. Thus the answer would be letter B. because it has the same variables but different in gender 
        
                    
             
        
        
        
Mutualism is when two organisms are involved and they both benefit where as parasites is when two organisms are involved, but one is benefitted while the other is harmed.
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Answer:
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Greenhouse gases are certain molecules in the air that have the ability to trap heat in the Earth's atmosphere. Some greenhouse gases, like carbon dioxide (CO2) and methane (CH4), occur naturally and play an important role in Earth's climate. If they didn't exist, the planet would be a much colder place.
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Answer:
Explanation:
yes its 3 foxes per square kilometer
 
        
                    
             
        
        
        
The number of fossils found, the fact that fossils are oftentimes just a cast/mold of the organism with no real remains, and no interbreeding.
As time moves forward, we still strive towards better methods to answer questions about extinct organisms.