If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?
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A5 to 4
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B3 to 2
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C2 to 1
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D5 to 1
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E6 to 1
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正确答案: E