In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.

Example input: Article: There are a lot of public libraries in Britain. These libraries have more than one hundred and fifteen million books, not including those libraries of public schools. Public libraries not only lend books, music records but also help children, patients in hospitals and others to get special play readings, film shows and so on. The first public libraries were founded in about the year 1850. Today's public libraries usually have a reading-room, a lending room and a reference room. The greatest and most famous library in Britain is that of the British Library in London. It was founded in 1973 and has over 10, 000, 000 books. It has nearly every magazine, newspaper and book published in Britain and other parts across the world.
Answer: 10,000,000 or less.
Example output: How many books are there in the British Library?
Example explanation: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.
Q: Article: It's flu season. What are you doing about it? David Oreck, Founder My Oreck Air Purifier captures and destroys viruses, bacteria and germs. 2005 ORECK HOLDINGS,LLC. All Rights Reserved. All word marks, logos, product configurations and registered trademarks are owned and used under the authority of Oreck Holdings, LLC. For the very young and the very old and virtually everyone in between, the flu is nothing to sneeze at. So here's what you can do. Check with your doctor to see if a flu shot is right for you. Wash your hands frequently. Maintain a healthy diet and regimen of exercise. And because you're spending most of your time indoors, it makes sense that the air in your home is as fresh, clean and pure as it can be. My Oreck XL(tm) Professional Air Purifier captures and destroys viruses, bacteria and germs. It removes mold spores, pollen, pet dander, household odors and other airborne particulates as small as 0.1 microns. (The flu virus measures 0.3 microns.) The Oreck Professional Air Purifier uses the same advanced technology as the prefix = st1 /U.S.submarine fleet where mariners are submerged for up to six months at a time. Because the permanent electronic filter never needs replacing, you can rinse it off as often as you like and it's as good as new. My Oreck Professional Air Purifier will literally pay for itself in what you pay for costly HEPA replacement filters that other manufacturers require. Besides HEPA filters don't destroy germs. They can only capture and hold them. So this flu season, take the Oreck Challenge and try my Oreck Professional Air Purifier risk-free for three full months. Then decide. CALL NOW AND RECEIVE A $100 GIFT-FREE. Just for trying an Oreck Air Purifier risk-free for 90 days, we'll send you our $100 Oreck Cord-Free Electric Broom ly free. It's a floor vac and a hand vac in one. If you don't feel the difference simply send the Air Purifier back--but keep the Electric Broom--there's no obligation. The shipping is free. Call 1-800-522-5961 ext. CR589 or visit www. oreck. com/decairNothing gets by an Oreck.
Answer: To persuade reader to buy his Air purifier.
A:
What's the author's purpose of writing this article?