Option (B) is correct.
To solve this question, we use two properties of eigen value of skew-symmetrical matrix of order 'n'
1) If n=odd,eigen value is 0.
2) if n = even,eigen values are pure imaginary.
Here n = 4(even),hence eigen values are +i,-i
Now for orthogonal matrix,eigen value is either 1 or -1.
Hence option is (B).
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