[单项选择]
The National Park Service
America’s national parks are like old friends. You may not see them for years at a time, but just knowing they’re out there makes you feel better. Hearing the names of these famous old friends-Yosemite, Yellowstone, Grand Canyon-revives memories of visits past and promotes dreams of those still to come.
From Acadia to Zion,369 national parks are part of a continually evolving system. Ancient fossil beds, Revolutionary War battlefields, magnificent mountain ranges, and monuments to heroic men and women who molded this country are all a part of our National Park System (NPS). The care and preservation for future generations of these special places is entrusted to the National Park Service. Uniformed Rangers, the most visible representatives of the Service, not only offer park visitors a friendly wave, a helpful answer, or a thought-provoking history lesson, but also are skilled rescuers, firefighters, and
A. Because they are always out there.
B. Because they are very old.
C. Because they make people feel better.
D. Because they are very famous.