The information in paragraph 12 helps to refine which of the author's claims?
A.
The United States' natural treasures are in many ways superior to those of other nations.
B.
There are a number of geographic features in the United States that cannot be found anywhere else.
C.
The beauty of the United States' mountains match that of any foreign mountain range.
D.
The establishment of the national park system has allowed Americans many new opportunities.
