Mechanical weathering occurs at a greater rate in climates that are a. cold and wet. c. hot and dry. b. warm and wet. d. cold and dry.

I believe that the answer is a.
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By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.

What have scientists learned about plant behavior by studying the dodder plant