Answer: d. outer surface
Step-by-step explanation:
Weathering is a phenomena of disintegration of the rocks or other materials into pieces or small fragments and sediments. The process of weathering takes place by physical and chemical agents.
The weathering of the rock takes place firstly on the outer surface which causes the disintegration of rock. The rock may be exposed to wind, water, temperature or chemical agents which causes change in the physical and chemical structure of the rock.