In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.

Let me give you an example: This list contains the top 25 accounts with the most followers on the social photo-sharing platform Instagram. As of May 2018, the most followed user is Instagram's own account, with over 235 million followers. Selena Gomez is the most followed individual, with over 137 million followers. Ten accounts have exceeded 100 million followers on the site.
The answer to this example can be: who has the maximum number of followers on instagram
Here is why: The answer is talking about the Instagram accounts that have the most followers. The question asking about the maximum number of followers. So this is a good example.

OK. solve this:
A world war, is a large-scale war involving many of the countries of the world or many of the most powerful and populous ones. World wars span multiple countries on multiple continents, with battles fought in many theaters. While a variety of global conflicts have been subjectively deemed 'world wars', such as the Cold War and the War on Terror, the term is widely and generally accepted only as it is retrospectively applied to two major international conflicts that occurred during the 20th century: World War I (1914 -- 1918) and World War II (1939 -- 1945).
Answer:
when does a war become a world war