I don't understand your question. What role did they play in what exactly? I could be able to help you if I knew what you were referring to.
The anti Imperialism league took a dim view of imperialism which meant they opposed the expansion b/c they believed imperialism violated the credo of Republicanism,especially the need for " consent of the governed."
There were several actions of the government around the turn of the century that social Darwinists would disapproved of, but one of the major ones was aid to the poor.
It all depends on the definition of the term Modern Era. The word modern comes from Latin word modo, which means right now or just now. It was used for the first time during the Renaissance in Italy to bring attention to the great rediscoveries of sciences, the arts, history and politics of Classical antiquity and the subsequent discoveries and progresses accomplished like the Age of Discovery.
If such definition is used as the basis for this question then the answer is definitely C.The establishment of global empires.
Indeed, since during the previous periods, Empires were limited to their immediate geographic areas. There had been some attempts to explore areas that were located much farther like the Vikings and their travels to Greenland and North America.
However, it was the Europeans: and to some lesser extent the Chinese, that actually discovered (in the literal sense of removing the cover) the Americas for the entirety of the world. The discovery paved the way for the emergence of Global Empires that were completely unprecedented in the history of humanity since they spanned several continents. For instance, the Global Spanish Empire Under Philip II of Spain in the 16th Century that spanned the continents of Europe, the Americas, Africa and Asia.
the answer is D, let me know if its the correct answer :)