Find the odd one out with respect to ploidy of the cells.
Tapetum is the innermost layer of the anther wall. They provide nourishment to the growing pollen grains. Its cells called tapetal cells contain dense cytoplasm generally along with more than one nucleus. Hence, it is polyploid.
Microspore mother cells are diploid spore-producing cells that undergo meiosis to give rise to haploid microspores in angiosperms.
Endothecium is a layer comprising of diploid cells present in the microsporangia. The cells of this layer helps in the dehiscence of anther.