Fog, the other three options would be too high in the atmosphere to cause visibility problems.
Answer:
These are my own words (this took a while)
Explanation:
President Abraham Lincoln issued the Emancipation Proclamation on January 1, 1863, as the nation approached its third year of bloody civil war. The proclamation declared "that all persons held as slaves" within the rebellious states "are, and henceforward shall be free."
The King and the pope led the two hierarchies that formed the cornerstone of
feudalism. Sometimes these two figures worked together but sometimes they clashed.
The story behind the Trail of Tears. That everywhere they cried on the way, a flower grow.
