What important role do sand dunes play?

the answer would be a)henry grady because he came up with the term "new south"

answer; i believe the correct answer is (crops);

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.

answer; to save lives and protect property;