Answer:
C. "We shouldn't have to pay to see rocks and trees we're already paying to protect."
The statement "We shouldn't have to pay to see rocks and trees we're already paying to protect." is an argument in support of the claim that national parks belong to the country and admission should be free for all taxpaying Americans. The statement suggests that because taxpayers are already contributing money to protect and maintain national parks, it is unfair for them to also have to pay to visit these parks. The argument is that the parks are a public resource and should be accessible to everyone without additional fees. The statement is trying to make the point that taxpayers are already contributing to the maintenance and protection of the parks, and therefore, admission should be free for them.