Which of the following processes form part of physical weathering?

1. Freezing, thawing and frost wedging

2. Salt weathering

3. Oxidation and reduction

4. Unloading and expansion

Select the correct answer using the code given below:

• Physical or mechanical weathering processes depend on some applied forces. The applied forces could be: (i) gravitational forces, such as overburden pressure, load and shearing stress; (ii) expansion forces due to temperature changes, crystal growth or animal activity; (iii) water pressures controlled by wetting and drying cycles.
• Some of the physical processes are: Unloading and expansion; Temperature changes and expansion; Freezing, thawing and frost wedging; and Salt weathering.

Oxidation and reduction is a type of chemical weathering process.