To ensure that we have 23 balls of the same color, we should consider the worst case scenario.

The worst case scenario would be if we take 21 white balls, 22 green balls and 22 blue balls. In this case we won't have 23 balls of the same color. After that, there will be only green and blue balls left in the jar and no matter which one we take next we'll have either 23 green or 23 blue balls. So, the minimum number of balls we should pick is 21 + 22 + 22 + 1 = 66.

Answer: D.

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I think the trick is in the scope shifting so 23 of one colour can be either in the jar by removing other marbles or outside the jar as a result of being moved out.

very tricky, and the wording is confusing.

23 of the same color must be left in the jar or outside?
if in the jar, then we need to take at least 21 out + 1 green and 32 blue or 21 white 24 green and 9 blue. but neither works, so it must be the case that we need to take out, and see if we have at least 23 of the same kind.
to make sure that we have 23 of the same kind, we need to take 21 white, 23 blue or green and 22 blue or green. this gives us a total of 66.
what is the source of this question?

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