I'm not 100% sure what the skill means, but I did hear about a "piaget's skill of centration"
(Favorable slogan) Virtue, mission, and destiny under God.
This slogan summarizes the three main points used by the advocates of the “Manifest Destiny” doctrine (virtue of the American people, a mission to change the “Old World” and the manifest destiny under God’s guidance). Considering the thesis of the “American exceptionality”, the country had the legitimacy to expand itself while spreading the values of freedom and democracy.
(Unfavorable slogan) Don’t plant in America’s soil the seed of imperialism! Say no to the right of conquest!
Many were critic with the “Manifest Destiny” doctrine and considered it to be belligerent and contrary to the Republican values. It constituted a call for aggression which was, according to their point of view, a contradiction with the democratic founding values of the country.
The answer is like the second choice, “Africa’s river systems made it easy for Europeans to reach the the African interior”. We can determine this is correct by cancelling out the other options.
1- yes, Africa WAS rich in natural resources, but the Europeans did not care much for that. They had come to Africa for trade and slaves.
3- similar to A, the Europeans weren’t there because they were running out of space, yes they did conquer and claim lands in Africa, but the purpose of them being there was goods.
4- a lot like C, but not very relevant at all, especially since at this time the Europeans who were traveling definitely did not farm, they wanted their goods already prepared.
Since the other options have been ruled out, I will explain 2 a little bit. Obviously, the Europeans had sailed to Africa. At first the remained on the edges of it, taking over ports and just sailing along picking up slaves and continuing west. A good example of an African river used by the Europeans is the Congo River. It branches out throughout all of Congo and it’s historical importance is that an explorer named Henry Morton Stanley used it to continue into Africa. Though he may not sound familiar, we’ve all heard the phrase “Doctor Livingstone, I presume”. It was Stanley who said this once meeting with him.