Based on the text and the available options, the statement that best summarizes a central idea is "the harsh policies of the Treaty of Versailles and the toothless authority of the League of Nations contributed to future tragedy and conflict."
The article that this question referred to is titled "The Treaty of Versailles and the League of Nations."
The text revealed that the League of Nations has no power to stop the like of Japan invasion of China, Soviet expansion, etc.
This situation would later lead to World War II.
Hence, in this case, the statement that best summarizes a central idea is in option D.
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