It protects us from harmful UV rays from the sun.
Pretty sure it’s air pollution
The answer is B. climate is the general weather pattern of an area over many years.
A glacial valley cross-sectional shape is a U shape whereas a stream valley is usually a V shape. The U shape comes from the scouring action of the alpine glaciers which carries rocks with it which can abrade the walls of the valley and the glacier occupies the whole valley so scours out such a shape whereas the stream cuts down and water washes in from the sides of the valley into the stream or river creating the V shape.