Because they share some cultures
The correct answer of this question is letter D option. African colonies of France and Britain joined the war effort on the side of the Allies because they thought it would bring them independence after the war. After the war, Roosevelt brought up the independence of the African colonies. Then democratic government was introduced to the colonies.
The completion of the Transcontinental Railroad greatly affected companies that made products in that it made it far easier for them to transport their goods over long distances to markets, which greatly increased profits and output.
Answer: C
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