My guess would be D. Agriculture.
Explanation:
The "doldrums" is a descriptive adjective for the corridor from around Earth closer to the equator when ships can become stuck in windless seas. In the horse elevations, where even the air moves down to towards the Earth's surface, the increasing jet stream eventually subsides.
<span>The region of the U.S. is most likely to have a population of predominantly Sewdish, Norwegian, Danish, German and Polish backgrounds is the Midwest.</span>
The type of sand dune that would most likely form if the sand supply is limited the wind direction is constant and vegetation is sparse would be a barchan dunes. It is a <span>crescent-shaped sand </span>dune<span> produced by the action of wind predominately from one direction.</span>
