What does sublimation refer to in terms of phase change?

Sublimation refers specifically to the phase change where a solid transitions directly into a gas without passing through the liquid state. In the context of the question, when ice sublimates, it changes directly into water vapor. This process bypasses the liquid phase entirely, which is characteristic of sublimation. Such an example is commonly observed in dry ice (solid carbon dioxide) as it transforms directly into carbon dioxide gas.

The other choices represent different phase changes; for instance, the change of water vapor to ice is known as deposition, and the transition from liquid water to steam is vaporization. The transition from gas to liquid is referred to as condensation. Understanding these terms helps clarify the unique process of sublimation as it specifically describes the direct conversion from solid to gas.