Answer: Choice D) {6, 12}
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Explanation:
The upside down U symbol means "set intersection". The intersection of two sets is the collection of all items that are in both sets at the same time.
In this case, only 6 and 12 are in both set A and set B at the same time, which is why choice D is the answer.
We can rule out choices A through C because 3 is not in set A (its only in set B).
Visually on a Venn Diagram, the intersection of the two sets will be shown as the overlapping region between the two circles A and B. So we'll have 6 and 12 in this overlapped region. The other values will go in their respective circles but not be in the overlapped region.
