The N-point DFT of a sequence x[n], 0 ≤ n ≤ N - 1 is given by
$$X\left[ K \right] = \frac{1}{{\sqrt N }}\sum\limits_{n = 0}^{N - 1} {x\left[ n \right]} {e^{ - j\frac{{2\pi }}{N}nK}},0 \leqslant K \leqslant N - 1$$
Denote this relation as X = DFT(x). For N = 4, which one of the following sequences satisfies DFT (DFT (x)) = x.
A. x = [1 2 3 r]
B. x = [1 2 3 2]
C. x = [1 3 2 2]
D. x = [1 2 2 3]
Answer: Option B
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