Select the solid.
A: fork
B: grape juice
C: air inside a bubble
The air inside a bubble is a gas. A gas spreads out to fill a space. The air inside a bubble fills all the space in the bubble. If the bubble pops, the air will spread out to fill a much larger space.
A fork is a solid. You can bend a fork. But it will still have a size and shape of its own.
Grape juice is a liquid. A liquid takes the shape of any container it is in. If you pour grape juice into a different container, the grape juice will take the shape of that container. But the grape juice will still take up the same amount of space.