A、To build fires. B、To conduct scientific studies. C、To train other staff members. D、To help visitors with any difficulty. D

Welcome to Yellowstone National Park. Before we begin our nature walk today, I’d like to give you a short history of our National Park Service. The National Park Service began in the late 1800s.
     (22-1)A small group of explorers had just completed a month-long exploration of the region that is now Yellowstone. They gathered around a campfire and after hours of discussion, they decided that they should not claim this land for themselves. They felt it should be accessible to everyone.(22-2)So they began a campaign to preserve this land for everyone’s enjoyment. Two years later, in the late 19th century, an act of congress signed by President Ulysses S. Grant, proclaimed the Yellowstone Park region a public park.(23)It was the first national park in the world. After Yellowstone became a public park, many other areas of great scenic importance were set aside. And in 1916 the National Park Service was established to manage these parks. As a park ranger,(24)I am an employee of the National Park Service. In the national park, park rangers are on duty at all times to answer questions and help visitors with any difficulty.(25)Nature walks, guided tours and campfire talks are offered by specially trained staff members. The park service also protects the animals and plants within the park.
Questions 22 to 25 are based on the passage you have just heard.
22. According to the speaker, who originated the idea of the public park?
23. What does the speaker say about Yellowstone National Park?
24. Who is the speaker?
25. According to the speaker, which is one of the duties of a park ranger?