The diagram below shows the different phase transitions that occur in matter. Three bars are shown labeled Solid, Liquid, and Gas. They are connected by arrows labeled 1 to 6. Arrow 1 points from liquid to gas; arrow 2 from solid to liquid, arrow 3 from solid to gas, arrow 4 from gas to liquid, arrow 5 from liquid to solid, and arrow 6 from gas to solid.

Which arrow represents the transition in which dew is formed?
1
2
4
6