If k$$S_n$$ is defined to be the product of (n + k)(n - k + 1) for all positive integers k and n,which of the following expressions represents k+1$$S_{n+1}$$ ?
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A(n + k)(n - k + 2)
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B(n + k)(n - k + 3)
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C(n + k + 1 )(n - k + 2)
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D(n + k + 2)(n - k + 1)
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E(n + k+ 2)(n - k + 3)
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正确答案: D