Answer:
I believe the printing press. Before the printing press books were very rare and expensive. Most religious scrolls were put on cloth or papyrus(a type of plant). After the invention of the printing press it made books less rare and expensive. And launched the world into a more modern era.
Its A, because Alexander the great was successful so it can't be B, the city states did unite to defeat persia so it can't be C, and Rome conquering Carthage is irrelevant because Carthage was in Africa so can't be D. Its A because sparta and Athens hated each other, after all the city states united to defeat Persia they separated again and eventually Sparta and Athens had the Peloponnese.
<span> The Spanish Flu of 1918 is the most recent. </span>
Following the French and Indian War, the victor (Britain) existed as the European power with the strongest colonial rule in North America due to demands made against France and the land taken at the end of the war.