Which technique is used to study structure of molecules -
X-ray crystallography
Ion exchange chromatography
Electron microscopy
Agarose gel electrophoresis
In the question, they have not mentioned about the nature of structure such as 1o, 2o or 3o etc. In this case, consider teiary structure (3D structure). So, mark X-ray crystallography (X-ray crystallography can detect 3-D structure of any macromolecule). ADDITIONAL INFORMATION ON THIS TOPIC Mass spectrometry: Best technique to determine-primary structure of proteins This technique is Qualitative as well as Quantitative Can detect post-translational modifications (like hydroxylation) or covalent modifications of enzymes (like phosphorylation and dephosphorylation) Can detect the exact molecular weight of the protein (as the name says - MASS).
Proteins bonds and structure