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Let $X$ be a proper closed subset of $[0, 1]$. Which of the following statements is always true?

1. The set $X$ is countable.
2. There exists $x \in X$ such that $X ∖ \left \{ x \right \}$ is closed
3. The set $X$ contains an open interval.
4. None of the above.
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What option B says here ??
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set minus notation.

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