Question

1. You have two boxes of colored pens. The first box contains a red pen, a blue pen, and a green pen. The second box contains a yellow pen, red pen, and a black pen. What s the set that represents all the pens
A. {red pen, blue pen, green pen}
B. {red pen}
C. {red pen, red pen, green pen, yellow pen, black pen}
D. {red pen, blue pen, green pen, yellow pen, black pen}

Answer 1

You dont get duplicates in the set so although there are 2 red pens it only appears once in the set.

So the correct answer is  D