Method (s) to determine protein structure is/are: (A) X-Ray Crystallography, (B) NMR Spectroscopy, (C) Infrared spectroscopy, (D) All of these
Answer is D. X-ray crystallography (X-ray diffraction)
UV light spectroscopy and infra-red spectroscopy
Nuclear magnetic resonance (NMR) spectroscopy
Polychromatic X-ray crystallography (Laue diffraction)  
Optical rotatory dispersion
Circular dichroism
Computer-based modelling
Mass spectrometry