Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Let me give you an example: Who was the first American President?
The answer to this example can be: president of the united states
Here is why: The question talks about the president of the USA.

OK. solve this:
The boundaries of four states of the USA, known as the Four Corners states, meet at one point, the only such geographic point in the USA. They are Colorado, New Mexico, Arizona and which other?
Answer:
four corners