18 should be the middle of the box and whisker plot. The whisker on the left should be at 16(smallest) and the whisker on the right should be at 23(largest). Answer D is the only one that fits this data.
Because the numbers are lined up from least to greatest all you have to do is find the middle of all the numbers which is 10. So everything below ten is lower quartile. Everything above is upper quartile
