The correct answer is A. Other countries were improving their militaries and growing stronger. England had been the preeminent European power throughout the 19th century since the defeat of Napoleonic France; however, at the turn of the century other countries were beginning to catch up, most notably Imperial Germany, which clearly had its sights set on replacing Great Britain at the top of the imperial food chain. This situation grew ever more tense and, thanks to what later came to be known as Thucydides's trap, led to World War I.