O and P are identical molecules.
(M and O) and (N and P) are two pairs of enantiomers.
(M and O) and (N and P) are two pairs of diastereomers.
bromination proceeds through trans-addition in both the reactions.
Addition of halogens is stereospecific reaction. Trans-2-butene gives meso product whereas the cis-isomer gives racemic mixture.