Answer: D. a "blue planet" covered mostly by water
Explanation: 71% of earth is made up of water
The answer is C) European settlers introduced corn and potatoes to North America.
They believed that Africans were uncivilized and needed to be guided by Europeans.
John McCain went on 23 combat missions, the twenty third being the one where he became a prisoner of war in Vietnam which became a famous thing. When he returned home he remained in the military but as a commander and didn't fly into combat missions.