In which one of the following regions of the Earth is the ozone hole prominently observed in the stratosphere?

The ozone hole is a phenomenon of severe depletion of the ozone layer in the stratosphere, most prominently observed over the Antarctic region. It occurs annually during the Southern Hemisphere spring (September to October).

The depletion is primarily caused by human-made chemicals like chlorofluorocarbons (CFCs) and halons. The unique meteorological conditions in Antarctica—specifically the Polar Vortex and extremely low temperatures—lead to the formation of Polar Stratospheric Clouds (PSCs). These clouds provide a surface for chemical reactions that release active chlorine and bromine, which rapidly destroy ozone molecules when sunlight returns in the spring. While ozone thinning is occasionally observed over the Arctic, it is significantly less severe and less frequent than the Antarctic hole due to higher temperatures and a less stable polar vortex. Equatorial and tropical regions do not experience such drastic seasonal depletion.