Which of the given statement(s) about N, O, P and Q with respect to...

The given conformation are of the following compound
Note : Fisher conformation always show the eclipsed form of molecule. Thus, we have to convert the given staggered conformation of 'O' to an eclipsed conformation.
Based on the above structures, we can say that (a) $\mathrm{M}$ and $\mathrm{N}$ are diastereomers or non-mirror image stereoisomers. (b) $\mathrm{M}$ and $\mathrm{O}$ are identical. (c) $\mathrm{M}$ and $\mathrm{P}$ are enantiomers. (d) $\mathrm{M}$ and $\mathrm{Q}$ are diastereomers and therefore not identical.