阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题纸上将该选项标号涂黑。
A
Starting school late should be the guiding principle (原则) for high schools around the Puget Sound District. Next year, Seattle’s Nathan Hale High School will join the growing. list of schools starting a little later to allow students an hour’s extra sleep. As a national research has shown, a later start time benefits students both in learning and physical development.
For school leaders, it isn’t easy to make the change. Bus schedules have to be rearranged, sometimes presenting the districts with a choice of keeping traditional starting times at high schools or forcing elementary students to start much earlier. Some sports practice and event schedules can also he affected.
