The correct answer is option 2, levees. Natural embankments found on upper valley sides are called levees. Levees are formed through the accumulation of sediment and debris over time, often deposited by rivers during flood events. These elevated landforms act as natural barriers or walls along the sides of a river or stream, helping to contain the flow of water within the channel. Levees are important for flood control as they prevent water from spilling out onto the surrounding floodplain and causing damage to nearby communities. They also provide a natural buffer zone between the river and the surrounding land, helping to protect the adjacent areas from erosion and sedimentation.