The Great Wall of China is one of the most famous landmarks in the world. The Great Wall is made up of many different walls and fortifications built over the course of more than two thousand years. The Great Wall is over 13,000 miles long.
Explanation:
All the other sentences seem a little off-topic. But the second sentence does it perfectly.
c) It will require the United States to spend money to defend the islands.
Explanation:
Carnegie believes that conquering the Philippines would cost the US money because it will require the US to spend money defending the islands from foreign invasion.