Answer:
The correct answer is 4) wind.
Step-by-step explanation:
While some plants can pollinate by water:
they are aquatic, and make it so their pollen floats on the water's surface drifting until it contacts flowers. This is called surface hydrophily. They are quite rare and only 2% of pollination overall.
Wind is most common, with around 12% of total pollination taking place in this method. Plants release billions of pollen particles, and the lucky ones will hit another plant sucessfully pollenating it. That's also why people have allergies, because of the plants releasing pollen out into the wind and air.
Hope this helped. :)