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If the difference between the expectation of the square of a random variable $\left(E\left[X^2\right]\right)$ and the square of the expectation of the random variable $\left(E\left[X\right]\right)^2$ is denoted by $R$, then

1. $R=0$
2. $R<0$
3. $R\geq 0$
4. $R > 0$

Catch is that Variance can never be negative.
Unless we are dealing with numbers with imaginary parts!