Answer:
A. Valley- Glacier, River
B. Landslide- Gravity, Tiles
C. Frost wedging- Ice
D. Canyon- River
Valley is a shallow regions formed between hills and mountains. The valleys are formed due to the flow of river or due to retracting glacier.
Landslide is a event which occurs in a hilly area or mountain region, in which large heavy rocks or tiles gets displaced down the hill due to the effect of gravity.
Frost wedging is a type of physical withering process. It involves the rapid freezing and thawing of rocks covered by ice due to changing weather conditions results in formation of wedge or cracks in the rock. It causes withering of rocks.
Canyon is a deep cleft which develop between mountain peaks by the flow of river.