Nearly 300 miles long, up to 18 miles across and 4000 vertical  feet down, the 8th new wonder: the splendid Grand Canyon . Viewing its glory, President Theodore Roosevelt called the Grand Canyon "a natural wonder,  ly unparalleled throughout the rest of the world". He urged Americans to preserve what he described as the "wonderful greatness, the nobleness, the great loneliness and the beauty of the canyon". More than a hundred years later, it's still easy to see why almost 5 million annual visitors call the Grand Canyon a wonder.  The canyon stretches as far as the eye can see. Some 5 or 6 million years ago, the Colorado River rushed through this land, carving out the massive canyon we see today, exposing even older layers of rock previously buried. Geologists say some are 2,000 million years old. Native Americans were the first people to make these rocky walls as their homes about 12,000 years ago.  Today the Hualapi and Havasupai Indians live deep in the canyon, balancing age-old traditions with modernity. There are no roads to this village; mules carry the mail here. But at the same time, the tribes are designing a skywalk that promises an excellent view over the canyon early next year. The bald eagle, wild and endangered American icon is another longtime resident of the Grand Canyon. The passage mainly introduces   _  .
the Arizona plains the bald eagle the Colorado River the 8th new wonder of the world : the Grand Canyon
Question: Nearly 300 miles long, up to 18 miles across and 4000 vertical  feet down, the 8th new wonder: the splendid Grand Canyon . Viewing its glory, President Theodore Roosevelt called the Grand Canyon "a natural wonder,  ly unparalleled throughout the rest of the world". He urged Americans to preserve what he described as the "wonderful greatness, the nobleness, the great loneliness and the beauty of the canyon". More than a hundred years later, it's still easy to see why almost 5 million annual visitors call the Grand Canyon a wonder.  The canyon stretches as far as the eye can see. Some 5 or 6 million years ago, the Colorado River rushed through this land, carving out the massive canyon we see today, exposing even older layers of rock previously buried. Geologists say some are 2,000 million years old. Native Americans were the first people to make these rocky walls as their homes about 12,000 years ago.  Today the Hualapi and Havasupai Indians live deep in the canyon, balancing age-old traditions with modernity. There are no roads to this village; mules carry the mail here. But at the same time, the tribes are designing a skywalk that promises an excellent view over the canyon early next year. The bald eagle, wild and endangered American icon is another longtime resident of the Grand Canyon. The passage mainly introduces   _  .
A. the Arizona plains
B. the bald eagle
C. the Colorado River
D. the 8th new wonder of the world : the Grand Canyon
Answer: