The well - designed experiment test one factor at a time. The answer to the question above is letter A. 1. The items that are being tested are the independent variables and that they cause the dependent variables to change.
        
                    
             
        
        
        
Answer: D. Species
Explanation:
Species is a group of population in which organisms have many common characteristics and they are capable of interbreeding and producing viable fertile offsprings. The members belonging to the same class and phylum have less common characteristics if they interbreed they may not produce viable fertile offsprings. Also, the organisms of the same kingdom have least common characteristics and will not have viable fertile offsprings after interbreeding. 
 
        
             
        
        
        
B) is the correct answer. The flu virus does not have the same genetic makeup each year as with each individual it infects its rapidly mutating.
        
             
        
        
        
B.) crystallization. Igneous rocks turn into sediments through the process of crystallization.