While you didn't really provide the "following" as the comment above me states, in general, the advantage of secondary sources of primary ones is that they perhaps provide a more objective or even just a broader view on a certain topic. While a primary source of the American civil war would be a letter written by a soldier, a secondary source would be a book that describes more letters taken together and discusses possible information regarding them.
The answer to this question is A. Jet streams
Jet streams are located near the altitude of the upper troposphere. It's a movement of wind that travels from one side of the planet hemisphere to another. The movement of jet streams will bring up different temperature of air which could influence the weather that exist in certain regions.
It was an example of a president using executive order.
<span>In response to riots over desegregation at the University of Mississippi, President Kennedy declare that C</span>