For a 400-year-old art form, opera had a bad fame: overweight actresses singing the words which were hard to understand in one of those romance languages you were supposed to learn in high school. And with tickets costing as much as $145 a performance, opera goers also had a certain appearance in people's mind: rich, well-dressed and old.[:] But now opera companies around the country are loosening their ties and kicking off their shoes in an attempt to keep opera alive and take it to a younger and not so wealthy audience. Opera producers have found that to attract this crowd, they need to make the opera closer to common people. Because young people don't or won't come to the opera, companies are bringing the opera to them, giving performances in such unusual places as parks, libraries and public schools. The Houston Grand Opera's choice is the public library, where it performs "mobile operas" shortened versions  of child-friendly operas. This summer's production is Hansel & Gretel. By performing smaller versions of large productions, producers are able to make people interested while keeping costs at a reasonable level. The San Francisco Opera, which will be celebrating its 75th anniversary this year, is staging Cinderella free of charge, keeping costs down by employing students from its Young Artists' Training Program. Which is the main idea of this passage?
Opera is famous for its long history. Opera is only performed for rich people. Opera companies are trying to keep opera alive. Young people are not interested in opera.