There's a good answer to that question.
This is right because I don't really know if there're is a real word.
The correct answer is 'Yellowstone National Park, the West's oldest national park, is the site of Old Faithful'. 'Yellowstone National Park', 'West', and 'Old Faithful' are all proper nouns, so they need to be capitalized. 'National park' does not need to be capitalized, because 'park' is a common noun, and 'national' is just an adjective describing it.
Hope this helps!
I would say the answer is a