Which sentence should be added to the end of paragraph 3 to support the ideas in the paragraph? Glacier National Park

Glacier National Park is a wilderness area in Montana. The park covers over one million acres. The park is open year-round and more than two million people visit each year. The terrain in the park varies from tall mountains to flat prairies.
The mountains in Glacier National Park are part of the Rocky Mountain range. They were formed long ago when tectonic plates below the earth's surface collided and caused the land to rise. These mountains are now home to animals such as bighorn sheep, marmots, and mountain goats. There are numerous types of trees near the base of most of the mountains, but the numbers and types of trees decrease as the elevation of the mountains increases. Visitors to the mountains can hike on the trails in the summertime and cross-country ski on the slopes in the wintertime.
In contrast to the high mountaintops, the prairies in Glacier National Park are found in low to mid-elevation areas. These wide, open spaces contain a variety of plants and animals. Wildflowers dot the landscape. Elk and prairie dogs roam the land. Visitors can go on a horseback ride or stay overnight at a campground.