单选题 In a speech to schoolchildren last week that had some conservative opponents up in arms, President Obama delivered at least one line that seemed incontestable (无可不论的): "I hope you'll all wash your hands a lot, and stay home from school when you don't feel well, so we can keep people from getting the flu this fan and winter. "The Disney corporation is now marketing Musical Hand Wash Timers featuring characters like the Little Mermaid, and encouraging parents to "take precaution against swine flu" by teaching children to wash their hands correctly. "Studies prove that regular hand - washing dramatically reduces the spread of infection," says the Disney Web page, which links to the Centers for Disease Control and Prevention's Web site.
What is the paragraph mainly about?

• A. It is publicized that hand - washing is an effective way to reduce the spread of swine flu.
• B. President Obama encouraged children to wash hands a lot to stay healthy.
• C. Disney corporation now is interested in public health affairs.
• D. Washing hands correctly is very important in reducing the spread of swine flu.