Glass A has scissors, Glass B has a paperclip, Glass C has an eraser, and Glass D has a watch. At first glance, people guess based on what looks “full,” but the trick is about volume, not appearance.
Objects displace water depending on their size—the larger the object, the less actual water the glass contains. So the glass with the smallest object holds the most water.
Answer: Glass B has the most water because the paperclip takes up the least space.