National Parks are:

a. An invention of the Romans, to overcome the "tragedy of the commons" that caused them to invade the food-service buildings of the neighboring Greeks.

b. A U. S. government program to provide roller-coaster rides for disadvantaged grandparents.

c. An invention of Greenlandic people, who set aside the northeastern part of the island as the world's first national park.

d. An invention of the United States that has spread around much of the world, as a way of protecting some of the finest parts of the world.

e. An invention of the United States, which has been routinely ignored by the rest of the world because they really don't like us.

The correct answer is D. National Parks are an invention of the United States that has spread around much of the world, as a way of protecting some of the finest parts of the world.

Explanation:

A national park is a park in which the protection of nature comes first, albeit almost always in alignment with human activities (in particular recreation, often also forestry, agriculture, hunting and fishing, sometimes mining) in and around the national park. The state usually recognizes the national significance of such a park and guarantees its protection. The term was coined in the US around 1870. Shortly thereafter the Yellowstone National Park was founded in a special area with geysers and bison among others. This park serves as an example for many other parks. Since then, hundreds of national parks have been established worldwide.