The correct answer is
C: The “war” was between etrog growers in Corfu, Greece and growers in Palestine, during the 19th century. Jews in eastern Europe, where conditions did not allow for growing etrogim, were purchasing from Corfu as those etrogim were considered the most beautiful in the world. But Jewish growers in Palestine claimed that the Corfu etrogim were not kosher, as they came from etrog trees grafted onto lemon trees (a process that produced hardier trees). The dispute continued into the 20th century, with the esteemed Rabbi Abraham Isaac Kook weighing in against Corfu etrogim, saying “The future, my brother, is with the kosher etrog, with the power of kashrut, and only with the kosher etrog will we win the battle of those who are against us, the Corfu mamzer [etrogim].”