Answer:
L, solid to gas
Step-by-step explanation:
Both gas and liquid have atoms that can slide past each other, where as, solids have atoms that vibrate in place. The paragraph states that, "Before the change, the atoms are close together and cannot slide past one another.." meaning that the atoms in the substance will be able to slide past each other after the change, and that the substance was a solid before the change. Look back in that text again and you'll find that it also says, "After the change, the substance can fill its container.." meaning that the substance can move freely within its containment system, and that the substance is gas. There was energy added to the electrons in this substance.. there are a few ways of doing that, but the process in which this situation does it is called "sublimation." Sublimation is a phase change where a solid has energy added to it and skips straight into the gas phase with no liquid phase in between. The arrow in the diagram labelled "L" is pointing from solid to gas, making this the answer.