You are presented with the quiz "What are factors in the creation of formations in the desert?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "sand dunes are formed by the wind transporting and depositing sand" and "aeolian erosion of sand in the desert is partially responsible for the formation of sand dunes". 

So, what's the best answer to the question?


 

        wind and erosion   