Answer:
A.mosses
Option A is the right answer
 
        
             
        
        
        
When levels decrease, the parathyroid releases hormones.
        
                    
             
        
        
        
Answer:
D.
Explanation:
It's the only choice that has three things that are made out of aluminum. 
<em>Hope this helps :)</em>
 
        
             
        
        
        
The correct answer is It would be more difficult for DNA to unzip since it would require more energy to break the bonds.
That is because it would most probably be a covalent bond and such a bond is stronger than a hydrogen bond which means that more energy would be needed to break it.
        
                    
             
        
        
        
Independent variable: FERTILIZER.
 This is the variable that you think affect your dependent variable and so you change it and use different types of it to confirm your prediction.
Dependent variable: COLOR. 
That is the variable you are interested in.
Hypothesis: THE TYPE OF FERTILIZER USED IN CULTIVATING HYDRANGEA FLOWER AFFECT THEIR COLOR.
 An hypothesis is a generalized statement which predicts the relationship between the variables you are examining. 
Control group: THE GROUP THAT DID NOT GET ANY FERTILIZER
The control group is the group that does not receive any treatment. 
Experimental groups: THE GROUPS THAT RECEIVED FERTILIZERS.
The experimental group is the group that receives treatment. 
Constants: TYPES OF SOIL USED, MORNING SUNLIGHT, WATER AND THE NO OF DAY THE EXPERIMENT LAST.
The constants are the inputs into your experiment which you give to all the groups.