I believe that is meiosis. If I am not right then search for it online
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Answer:
Sigma factors bind to the promoter region of a particular gene and facilitating the binding of RNA Polymerase to the promoter region (formation of the RNA polymerase holoenzyme complex) in order initiate transcription of the gene. 
Put simply - Helps RNA Polymerase do it's job. 
 
        
             
        
        
        
Answer:
D. Cyclin
Explanation:
Cyclins drive the events of the cell cycle by partnering with a family of enzymes called the cyclin-dependent kinases (Cdks). A lone Cdk is inactive, but the binding of a cyclin activates it, making it a functional enzyme and allowing it to modify target proteins.
 
        
             
        
        
        
It's Out Of C Or D Because It Explains It