"Tropopause folding" occurs when the stable stratospheric air intrudes under tropospheric air under the jet stream. It can be seen as a sharp gradient in the grey shades of water vapour images.
If you look at the wv image alone (see below), where you can get an indication of the jet streaks? There are two correct areas!
If you have correctly idetified the areas, you can see the answer in this additional image.