Diffusion is a passive movement. The correct answer is b
        
             
        
        
        
Answer and Explanation:
Platyhelminthes are mostly worm like organisms that are dorsoventrally flattened, meaning they look like a leaf and this is why they are coined names like the Tapeworm, Flatworm, Fluke and Planarian.
 Most Platyhelminthes are parasites on other animals but only the Turbellarians are mostly non-parasitic. A few species are commensalists, or mutualists living with other larger organism.
They are classified into:
- Class Turbellaria 
- Class Monogenea 
- Class Trematoda 
- Class Cestoda
 
        
             
        
        
        
 
 
Darwin would be happy that his theory of evolution is correct. Stating that biological evolution is through natural selection of inherited traits that enable a species to survive, compete and reproduce. 
 
        
             
        
        
        
<span>1.      
</span>They act as activators of transcription. This is
through increasing the affinity of the RNA polymerase on the promoter
<span>2.      
</span>They could act as repressors. This way, when
they bind to their active sites, they
repress the binding of the RNA polymerase on the promoter
<span>3.      
</span> Transcription factors at one site could affect transcription of genes on another site on the
DNA. The flexibility of the DNA (by forming loops) allows for this phenomenon.