Catch is that Variance can never be negative.

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**Answer is (C)**.

The difference between $(E[X²])$ and $($$E[X]$$)$$^{2}$ is called variance of a random variable. Variance measures how far a set of numbers is spread out. (A variance of zero indicates that all the values are identical.) A non-zero variance is always positive.

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This the definition definition of variance . Variance never be negative.Variance is the average squared deviation from the mean. Notice the word “squared”. It may be zero. Variance of constant is zero.Theorem 2 a

Answer C