The correct answer is option 3, Gully. A gully is a landform that is formed by the action of rainwater. When rainwater runs off on the surface of the land, it creates channels and erodes the soil, creating a gully. Gullies are typically deeper and wider than rills, which are smaller erosional channels.

Let`s now analyze the other options:

- Option 1: Gorge - A gorge is a narrow and deep valley with steep sides. While rainfall may play a role in the erosion that forms a gorge, it is not solely produced by rainwater action. Gorges are often formed through the action of rivers or glaciers.

- Option 2: Cliff - A cliff is a vertical or near-vertical rock face. While weathering processes, including rainfall, can contribute to the formation of cliffs, they are not exclusively produced by rainwater action. Other processes such as erosion by wind, waves, or rivers can also contribute.

- Option 4: Dome - A dome is a rounded topographical feature formed by various geological processes, but rainwater action is not typically responsible for its formation.

In conclusion, the correct answer is option 3, Gully, as it is directly produced by rainwater action.