The united states gained islands in the Eastern Samoan Islands.
Because of the ocean and the Himalayan mountains , china was able to grow on its own and did not have much influence from other civilizations
A and D. Russia signed the treaty with the Central Powers (Germany, Austria-Hungary, Ottoman Empire, Bulgaria)
The answer for that would be "A, Land west of the Mississippi River was not good for farming" because according to answers.com, it says " People moved to the west because in the east there was no room for farming, economic depression, and there was no space for agriculture." So in this case, it is "A". Hope this answered what you needed. Ask me more questions and I will be sure to answer them. :)