Answer:
B) gravity, lichens and moss, tree roots
Explanation:
In this mountainous area of Canada, weathering of rocks occur due to the force of gravity which increases the speed of rolling rocks and causes weathering of rocks into small pieces. These rocks have hard surfaces so only moss and lichens grow on these surfaces. The reason behind the growth of moss and lichens is that they have not specialized root system like plants. Lichens also helps in the weathering of these rocks by secreting chemicals.