This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
The teiary structure of protein is determined by 
Select and explain. 
A. X-ray Crystallography, B. Spectrophotometry, C. Electrophoresis, D. Chromatography
A: X-ray Crystallography
Answer: A: X-ray Crystallography 
Explanation: Three-Dimensional Structure is determined by X-ray Crystallography or by NMR SpectroscopyRef: Harper&;s Biochemistry; 30th edition; Chapter 5; Proteins: Higher Orders of Structure