During which transition are molecules moving farther apart?
a. water falls over a cliff.
b. rain turns to snow.
c. steam forms water droplets.
d. water boils.

The answer is letter B.

When water boils, the process of evaporation occurs. This means that the liquid phase of a molecule turns into a gas phase. Liquid molecules are more compact or closed together compared to gas molecules. When evaporation occurs, liquid molecules move farther apart from each other which then turns the liquid into vapor. When this happens, molecules move freely in the form of gas molecules which are less dense than liquid.