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Let $X$ be a real-valued random variable with $E[X]$ and $E[X^{2}]$ denoting the mean values of $X$ and $X^{2},$ respectively. The relation which always holds true is

1. $(E[X])^{2}>E[X^{2}]$
2. $E[X^{2}]\geq (E[X])^{2}$
3. $E[X^{2}] = (E[X])^{2}$
4. $E[X^{2}] > (E[X])^{2}$