Starting with the breakup of Imperial China in 1911, China became an area where warlords would control the lands. Nationalist China, which claimed all of China had a sizeable minority of Communists, and when the Nationalists banned Communism, the Communists rebelled and created their own state. When Japan invaded China in 1937, the Warlords combined to fight Japan and after Japan's defeat in 1945 the warfare resumed. Due to the war with Japan though, the Nationalists were very weak. When the Communists resumed the fighting, the Nationalists couldn't keep up and had to evacuate to the island of Taiwan, where they still keep their Democratic system. Mainland China fell to the Communists, and both claim each others lands citing themselves as the "true" China.
One thing scientists in the late 1700s could determine about the fossils they were finding were fossils in the upper layers were younger than fossils in lower layers. The correct answer is A.
