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Topology

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Moderate

Open and Closed Sets in Rn 2

TOPO-XEVJXN

Which one of the following statements is true in $\mathbb{R}$?

Select ALL that apply.

A

The union of a finite number of open sets is open

B

The intersection of a finite number of closed sets is closed

C

the intersection of a finite number of open sets is open

D

the union of a finite number of closed sets is closed.