Among the following, the Newmann projections of meso-2,3-butanediol are:

Meso-2,3-butanediol has the following structure:

For meso-2,3-butanediol, the two chiral carbon atoms must have opposite configurations:$$(2R,3S)\quad\text{or}\quad(2S,3R)$$

A meso compound is achiral despite having two stereocentres because it possesses an internal plane of symmetry.

P:The arrangement of the groups about C-2 and C-3 gives opposite configurations at the two stereocentres:$$R,S$$
Hence, P represents meso-2,3-butanediol.

Q:Both stereocentres have the same configuration:$$R,R$$
Therefore, it is a chiral form, not meso.

R:The arrangement again gives opposite configurations:$$R,S$$

It has the required symmetry and represents meso-2,3-butanediol.
S:The two stereocentres have the same configuration:$$R,R$$
Hence, it is chiral, not meso.

Correct option: (B)