【单选题】

{$mediaurl} Why does the professor mention permafrost in the Himalayas

A、To explain that certain conditions are necessary for the formation of permafrost.

B、To suggest that permafrost is more common than many people believe.

C、To emphasize the changes in permafrost that have occurred due to global warming.

D、To illustrate that alpine permafrost can be found at low latitudes.