The event that brought about Japanese being worried about how their defense over vast empire make the spreading of their resources in thin line is C: The bombing of Pearl Harbor.
- The attack on Pearl Harbor can be regarded as a surprise military strike which was carried out on the United States by the Imperial Japanese Navy Air Service, and this occur at Pearl Harbor in Honolulu in 1941.
- This event were the reason why the Japanese were so worried on how they were controlling the vast empire and how this is affecting their resources.
Therefore, option C is correct.
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