1. Cyrus McCormick
2. Sewing Machine
3. Samuel Morse
4. Eli Whitney
5. Cotton Spindle
6. Cotton gin
7. Charles Goodyear
8. John Deere
9. Francis Lowell
I do not know the answer, but if I were to guess, that it would be the one about plantations.
Plantations were hotspots of manual labor, specifically slaves. And when slaves were outlawed the plantation owners lose there main source of “profit” (aka the need to not pay workers for manual labor and instead use that money to get more laborers) it seems like the logical answer to me.
Also using process of elimination we know that the war could have spilt the country in two. So the union was indeed saved.
Hitlers Family Doctor was a Jew. The doctor failed to save his mothers like (who he was very very close to) leading to her death from Breast cancer.