"C. was overthrown by invading Mongol tribes in A.D. 1279" would be the best phrase describing China's Song Dynasty, but this was of course not always the case.
Answer: #1 is option b and #2 is C
Manifest Destiny held that the United States was destined—by God, its advocates believed—to expand its dominion and spread democracy and capitalism across the entire North American continent. Manifest Destiny, a phrase coined in 1845, expressed the philosophy that drove 19th-century U.S. territorial expansion.