This change best illustrates the 3rd answer choice, Loss of Habitat. 
The plants aren't migrating, but are rather only surviving in areas where there is enough moisture to support life. The wildflowers are not adapting to grow in dryer conditions, and the species is not going extinct, as there are still some areas where the plants can get enough moisture. 
Hope this helped!
 
        
                    
             
        
        
        
A: In a lab a scientist measures the height of roses that received different fertilizers. 
An experiment must include variables. The other three are just measurements, but since the scientist is varying the types of fertilizers used, this better describes an experiment. It is also done in a controlled environment (in a lab) which helps to eliminate other uncertainties.
        
             
        
        
        
Answer:
Out crossing
Explanation:
By breeding a certain breed of chicken with a different kind of chicken may produce different sized eggs and avoid the possibility of inbreeding depression