I have found the question online. We are supposed to choose which sentence is unrelated to the main idea in the passage.
Answer:
The sentence that is unrelated to the main idea in the passage is:
Located in the state of California in the Sierra Nevada Mountains, Yellowstone National Park is a perfect place to take a vacation.
Explanation:
Out of the five sentences in the passage, four are related to the main idea. Those four sentences all talk about the importance of conservation and preservation of certain areas. They explain, for instance, that the US government has chosen certain places to preserve, that there is a difference between conservation ad preservation, that certain types of areas are chosen, and finally, that Yellowstone is one of those areas. So far, so good. However, the very last sentence takes an abrupt turn when it states that Yellowstone is a perfect place for a vacation. This has nothing to do with what the other four sentences discuss, and there was no transition or progression to this new subject. It was sudden and, therefore, unrelated.
With that in mind, the unrelated sentence is:
Located in the state of California in the Sierra Nevada Mountains, Yellowstone National Park is a perfect place to take a vacation.