Which of the following statements is true about un

单项选择题

The National Park Service America’s national parks are like old friends. You may not seethem for years at a time, but just knowing they’re out there makes you feelbetter. Hearing the names of these famous old friends-Yosemite, Yellowstone,Grand Canyon - revives memories ofvisits past and promotes dreams of those still to come. From Acadia to Zion, 369 national parks are part of a continuallyevolving system. Ancient fossil beds, Revolutionary War battlefields,magnificent mountain ranges, and monuments to heroic men and women who moldedthis country are all a part of our National Park System (NPS). The care and preservationfor future generations of these special places is entrusted to the NationalPark Service. Uniformed Rangers, the most visible representatives of theService, not only offer park visitors a friendly wave, a helpful answer, or athought-provoking history lesson, but also are skilled rescuers, firefighters,and dedicated resource protection professionals. The National Park Service ranksalso include architects, historians, archaeologists, biologists, and a host ofother experts who preserve and protect everything from George Washington’steeth to Thomas Edison’s wax recordings. Modern society has brought the National Park Service both massivechalienges and enormous opportunities. Satellite and computer technologies areexpanding the educational possibilities of a national park beyond it’s physicalboundaries. Cities struggling to revive their urban cores are turning to the ParkService for expert assistance to preserve their cultural heritage, createpocket parks and green spaces, and re-energize local economies. Growingcommunities thirsty for recreational outlets are also working with the NPS toturn abandoned railroad tracks into bike and biking trails, as well as giving unusedfederal property new life as recreation centers. To help meet these challenges and take advantage of theseopportunities, the National Park Service has formed partnerships - some datingback 100 years, some only months old -with other agencies, state and local governments, corporations, American Indiantribes and Alaska Natives, Park Friends groups, cooperating associations,private organizations, community groups and individuals who share the NationalPark ethic. National Park Week 1996 is a celebration of these partnerships.

Which of the following statements is true about uniformedrangers

A．They take tourists to national parks.
B．They always act as tourist guides.
C．They help set up new national parks.
D．They protect the National Park System.