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.

Example input: 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.
Example output: who has the maximum number of followers on instagram
Example explanation: 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.
Q: The Codd bottle was designed and manufactured to enclose a marble and a rubber washer / gasket in the neck. The bottles are filled upside down, and pressure of the gas in the bottle forced the marble against the washer, sealing in the carbonation. The bottle is pinched into a special shape to provide a chamber into which the marble is pushed to open the bottle. This prevents the marble from blocking the neck as the drink is poured.
A:
why did old bottles have marbles in them