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.

Let me give you an example: 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.
The answer to this example can be: How many books are there in the British Library?
Here is why: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.

OK. solve this:
Article: Two men dressed as police officers stole about $200 million worth of art from the Isabella Stewart Gardner Museum early this morning. The two burglars knocked on a side door of the museum at about 1:15 am. They told the two security guards on duty that there was a disturbance in the area. The guards then made the very serious mistake of allowing the two men to go into the building. After they went in, the two burglars tied the guards up with tape. The two men stole 11 paintings and an ancient Chinese vase. The stolen works included three paintings by Rembrandt. A maintenance worker discovered the two guards at about 7 am and called police. One of the greatest losses was Rembrandt's works, "The Storm on the Sea of Galilee." It was a very popular attraction at the museum and was one of the most valuable works stolen. Museum officials said that the value of the stolen art is at least 200 million dollars, and may in fact be much more. The true value of the paintings is unknown, because they have not been on the market for nearly a century. This is considered to be the biggest theft ever in the United States. Officials are waiting to see whether the burglars will or try to sell them to a private collector. Museum officials and police are not sure why the burglars chose certain works and not others. There are other paintings in the museum that are even more valuable than the ones that were stolen. Special investigators are looking into the theft and the museum's security system. They believe that this is a "professional job," because the people involved were well prepared and knew what they wanted.
Answer: The security guards opened the door for them.
Answer:
How did the two burglars get into the museum?