When viewing the image of Sam's backyard, we can see the occurrence of chemical and physical weathering. Physical weathering is caused by the impact of water on rocks, which promotes the breakdown of rock particles. The chemical weathering is also caused by the water that I contact with the rock react with its elements causing chemical reactions that modify the rock.
Regarding erosion, we can consider the erosion by gravity that is common in mountainous regions, like the one shown in the photo. This type of erosion promotes the loss of mass of the rock due to the detachment and rolling of rock particles, due to gravity. We can also notice the rain erosion, created by the impact of water on the rock that detaches the fragments and transports them to other places.
He was a close friend to Charles Darwin so he helped him out in creating the theory of evolution so I would say C: He developed the idea of inheritance of acquired characteristics.
