Answer:
In his famous "House Divided" speech of 1858, Lincoln predicts that if the issue of slavery isn't rectified then the United States will not be able to endure in its present condition. Instead of being "half slave, half free" it will have to become completely one thing or the other, wholly slave or wholly free.
I would personally recommend the Ben Carson interview simply because it is constantly updated unlike the Encyclopedia Britannica.
Also, taking into consideration the fact that the main focus should be learning about a modern hero is important to highlight the fact that The Encyclopedia provides facts and general information regarding past heroes and despite Carson's controversial opinions he has had plenty of experience interviewing modern day heroes therefore I consider he would be a great resource.
Hope this helps!
Something from a teacher, professor or from a book
It would most likely be b.what is happening in the story