the answer is basically the scientific method.
Answer:A. Most had little direct connection, because they owned small farms.
Explanation:
They prevented people from leaving China because the desert were so hard to cross.(ANSWER D) Gobi desert was dangerous and dry, water available was little since oasis were rare. The Taklamakan desert has strorms with whip up frequency The day boils hot while the night freeze cold .In addition it has poisonous snake.
Civilization? I don't know the song/poem, so according to what ai have here this is my best guess...
Sorry I can't hell more!