All of the following share the same crystal structure except: LiCl, NaCl, KCl, RbCl

RbCl, NaCl, and KCl share the same crystal structure except for LiCl. LiCl is deliquescent. It crystallizes as a hydrate LiCl·2H₂O. Other alkali metal chlorides do not form hydrates. Hence, option C is correct.