That is, if the option choices are as follows: a. Most new territory added to the Union after 1850 would likely be slave states, which made the North nervous. b. Northerners felt slavery was an economic disadvantage to white people also. c. The anti-slavery movement in the North was gaining momentum in the second half of the 1800s. d. Compromises made by Congress to balance the power between slave states and free states were not working.
Japan is a island country, or in other words an archipelago. Hence, it was hard for other imperial countries to invade Japan. Japan also isolated itself from the rest of civilization.
