This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Interaction involved in primary structure of protein ? 
Select and explain. 
A. Hydrogen bond, B. Disulfide bond, C. Peptide bond, D. Electrostatic bond
C: Peptide bond
Answer: C: Peptide bond 
Explanation: Ans. is `c' i.e., Peptide bond