- Erosion is when wind transports sediments
- Sand is a kind of sediment
- Deposition is when wind deposits sediments
- Hence, wind erosion and deposition can transport and deposit sand

- Wind erosion and deposition can transport and deposit sand
- Sand dunes are formed by the wind transporting and depositing sand
- Therefore, sand dunes are formed by wind erosion and deposition

Therefore, sand dunes are formed by wind erosion and deposition
Question: Two processes are involved in the formation of a sand dune. Which two processes best describe how a sand dune forms?
Context: - Sand dunes are formed by the wind transporting and depositing sand 
- Erosion is when wind transports sediments 
- Sand is a kind of sediment 
- Deposition is when wind deposits sediments