Which of the following may be separated by ordinary physical methods? Select one: O (2R,3S)-1,2-dibromobutane and (25,3R)-1,2- dibromobutane O (R)-3-bromo-1-butene and (S)-3-bromo-1-butene O (R)-2-bromobutane and (S)-2-bromobutane O cis-2-bromo-2-butene and trans-2-bromo-2-butene