The freshet is basically a flood that occurs because of heavy rainfall or because of the melting of a snow.
This type of flooding is most common in the valleys of the larger rivers, especially the ones that start their flow high in the mountains.
The large rivers have much more water, and they also have lot of tributaries, so when there's a heavy rainfall they receive enormous amounts of water, which easily causes a flood.
Also, when the snow melts, lot of water is released from it, and most of that water gets into the river, or first in its tributaries and that in it, so there's a high possibility of a big flood occurring suddenly.
Answer:
I believe the answer is B.
In relation to the Andes mountain, the Atacama desert is located to the west. It actually lies between the pacific ocean and the Andes mountain. The Atacama desert is one of the driest place on earth. It is a rainless pleatue located in Southern America. The Atacama desert covers almost a 1000 kilometers. The desert mainly consists of salt lakes, rocks and sand. This is a place where rain occurred numerous years ago and so it is considered a totally rainless place. There is every probability that the Atacama desert is the oldest desert present in the earth.