The correct answer is "A".
The Wilmot Proviso in 1846 was an unsuccessful attempt to ban slavery in the territories acquired from Mexico after the events of the Mexican-American War. It was proposed by Congressman David Wilmot to the House of Representatives. It would eventually pass the House of Representatives but fail to pass the Senate.
The disagreements over this proviso were one of the events that led to the American Civil War.
The correct answer is (D): The tilt of the Earth on its axis changes during the year.
Earth revolves around the Sun as it spins on its axis of the rotation once a day. While the Earth orbits the Sun, the tilt of Earth's axis stays lined up with the North Star resulting to the North Pole tilting towards the Sun. The Northern Hemisphere is normally tilted toward the sun on the summer solstice while the southern hemisphere is tilted toward the sun on the winter solstice. Northern Hemisphere hence expects a change in days length where the days change from short days in the winter to long days around the summer solstice on June 21st.
The absence of a uniform tariff rate benefited British exports to America.
The Electoral College should remain the same for various reasons. First, if it were not for the Electoral College, large states, such as California, would largely control the nation. The Electoral College is designed to maximize states' rights. For example, if the U.S. were a direct democracy, Hillary Clinton would have been elected as our president, even though approximately 90% states supported Trump. With the Electoral College, each state has 2-3 Electors for each Political Party. If the majority of the state votes for Hillary, the democratic electors for that specific state get the vote. If the majority of the state votes for Trump, the Republican electors get the vote. The system is designed to maximize sates' rights and avoid impulsive, mass decisions.
The Middle Colonies were more diverse than colonies in New England and the South. Most of the early settlers depended on the fur trade and on farming for economic survival. The most populous of the Middle colonies was Pennsylvania, other colonies were settled rather haphazardly over the course of the 17th century.
