The correct answer is C. Flowing.
A mountain is a large landform that rises significantly above the surrounding land, while a hill is a smaller landform that rises above the surrounding land but is not as high as a mountain. A river is a natural stream of water that flows in a channel on the surface of the land.
The relationship between mountain and hill is similar to the relationship between river and stream. A mountain is a larger landform than a hill, just as a river is a larger body of water than a stream. Both mountains and rivers are natural features of the landscape, and both can be found in many different parts of the world.
The other options are not as closely related to mountain and hill as flowing is. A path is a human-made trail, while swimming is an activity that people do in water. A tank is a large container that holds liquids or gases, and it is not related to mountains or hills in any obvious way.
