B la patogenicidad de un virus
        
             
        
        
        
The bond formed between the sugar of one nucleotide and the phosphate of an adjacent nucleotide is a covalent bond. A covalent bond is the sharing of electrons between atoms. A covalent bond is stronger than a hydrogen bond (hydrogen bonds hold pairs of nucleotides together on opposite strands in DNA).
        
                    
             
        
        
        
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Answer:</h2>
The correct answer is option D which is that endocrine control can control melatonin.
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Explanation:</h2>
As melatonin is released from pineal gland which is a part of endocrine system.The endocrine system is a chemical messenger system which has glands, which secretes certain chemicals known as hormones.These hormone acts on different organs to control different metabolisms in body.So melatonin which is hormone can be controlled by the endocrine system.