Answer:
The answer to the question: Which of the folloowing was a key difference between the Triple Alliance and the Triple Entente, is, D: The Entente was formed in response to the threat of the German-led alliance.
Step-by-step explanation:
Although the conflict that led to the First World War, and the formation of the two bands: the Triple Entente (Britain, France and Russia), and the Triple Alliance (Germany, Austria and for a time Italy, who later on changed sides), was minor in size, with only Serbia and Austria in apparent fight, this changed rapidly with the dangerous game that Germany decided to play against the French, and also the game played by the Russians. On August 2, 1914, Russian forces, invaded German soil, and in response, the Germans activated their famous Plan Schlieffen, with which, they initiated an invation of France, and thus forced also the entrance into the war of Great Britain. This German invasion to France, and the German threat to Russia, forced then the formation of the Triple Entente, and in turn, this forced the alliance between Germany, the Austrio-Hungarian Empire, and for a time, Italy.