The statement is - True.
Glaciers affect the forming of the mentioned landforms with their movement.
The fjords form when a glacier forms a deep valley close to the shore like and after that the level of the sea rises and floods the valley, thus making elongated water bodies that penetrate inland and have vertical high rocky walls upwards.
The glaciated valleys are formed when a glacier moves through a certain place and with it's weight and pressure makes a valley like relief according to its own form.
The horns are created when glaciers are eroding three or more aretes and with it leaving the central part untacked which in the end is left to look like a sharp-edged peak while the sides around it are eroded by the glaciers.