Order the Steps That Are Needed to Determine the 3D

Multiple Choice

Order the steps that are needed to determine the 3D structure of a protein by x-ray crystallography.
I. diffraction pattern recorded using a diffractometer
II. data analysis
III. protein crystallization
IV. protein expression and purification

A) I, II, III, IV
B) IV, III, I, II
C) II, I, IV, III
D) III, I, II, IV
E) IV, I, II, III