I believe the answer is "a. Nationalism." ***I might be wrong.
Explanation:
Regarding any Indian conflict in the North American theater of the Seven Years War, the British and French were disputing over territory of the Ohio River Valley, thus showing how both countries were very greedy to obtain land for themselves and show off their prowess and superiority to each other. I feel like answer choices B and C just don't seem applicable, because the throes of the Seven Years War occurred in the midst of early imperialism, which is all about nationalism and not really about revenge, economics, or Indian conflict. Besides, this question is inaugurated with "like most wars," meaning that the answer choice must be common to wars such as World War II or the Mexican-American war. As any historian notices, nationalism is one of the most prevalent characteristics of any conflicts between multiple sovereign states.
One of those who heard about the discovery was John D. Rockefeller. Because of his entrepreneurial instincts and his genius for organizing companies, Rockefeller became a leading figure in the U.S. oil industry. In 1859, he and a partner operated a commission firm in Cleveland
Cornelius Vanderbilt became one of the richest people in the world by investing in the shipping and railroad industries. He is one of the richest Americans in history to this day.
