Diploblasty is a state of the blastula in which there are two essential germ layers: the ectoderm and endoderm. Diploblastic living beings are life forms which create from such a blastula and incorporate cnidaria and Ctenophora, earlier assembled together in the phylum Coelenterata, yet later comprehension of their disparities brought about their being put in discrete phyla.
To answer the above:
Diploblastic animals have ectoderm and an endoderm as well as radial symmetry.
        
             
        
        
        
I believe (B) is the best option due that it mentions the reason causing natural selection with limited supplies competition increases making it more likely for the strongest individuals to survive
        
             
        
        
        
Because you would not want to change anything in your experiment you are just changing what you are observing
        
             
        
        
        
<u><em>I believe it is A</em></u>) because i pulled research and says this...
<u><em>Research:</em></u> The slight positive charges on the hydrogen atoms in a water molecule attract the slight negative charges on the oxygen atoms of other water molecules. This tiny force of attraction is called a hydrogen bond. 
Hope this helps...