Meso compounds do not show optical activity because

Step-by-step solution

Meso compounds are those compounds whose molecules are superimposable on their mirror images inspite of the presence of an asymmetric carbon atom. This is due to internal compensation. The two halves of the molecule rotate the plane of polarised light in opposite direction and hence cancel the effect of each other and make the molecule optically inactive. Thus, the optical inactivity in meso compounds are because of plane of symmetry or molecular symmetry or internal compensation.