The correct answer is - c. Physical weathering is mechanical breakdown, while chemical weathering involves the chemical breakdown of substances.
The physical weathering comes as more extreme, and it is a process where force is used in order for the rocks to break, while the chemical weathering is causing corrosion, usually on the surface, and it involves slow and gradual dissolving through the interactions of different chemicals with rocks.
For example, if water manages to penetrate into a rock, and when its cold it freezes, the ice starts to expand and increases its volume, thus creating huge pressure inside of the rock, and eventually breaks it into multiple pieces, and that is a physical weathering. On the other hand, if rain is a common occurrence, and a rock is exposed to it, the rain will start to oxidase it, and little by little weather the surface of the rock until it manages to totally destroy it over a long period of time, and that is a chemical weathering.
