The correct answer is - A. Glacial erosion forms wide, U-shaped valleys.
The glaciers are essentially large masses of ice, formed either by large mas of snow or a frozen river. Because the ice is expanding, but also the glaciers appear at higher places and slowly move towards lower parts, they contribute to a lot of erosion. The size and their weight, plus their movement and the pressure they make, the glaciers manage to erode lot of material, and by doing so, they reshape the landscape in accordance to their form, which is an elongated, river like, U-shape. Once they are melted, the glaciers leave behind them long and narrow U-shaped valleys, some of which remain as a valleys, while others are filled with sea water and formed the fjords.
