Answer: B) 4
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How I got this answer:
Start off by using the roster method to list all the elements of each set. If there are infinitely many members of any set, then we use a pattern of 3 dots to indicate the pattern continues on forever.
set D = {0, 1, 2, 3, 4, 5, ...}
set E = {1, 4, 9}
set F = {2, 4, 6, 8}
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Focus on set E and set F right now. We see that only '4' is in both sets at the same time. So this means
E intersect F = {4}
we can then update the original question from "D intersect (E intersect F)" into "D intersect {4}" which is the same as asking "{0,1,2,3,4,5,...} intersect {4}"
Once again, only 4 is in both sets at the same time, so the final simplified set is {4}. The only member of this set is 4.
