Answer:
The landform marked with A is an ox-bow lake.
Explanation:
In the image, we can see a river and another fluvial landform right next to it. The river is meandering, moving through the plain in a zig-zag manner. The landform next to it has a half-circular shape, and it seems as it has been attached to the river until recently. In fact, the landform next to the river has been a part of the river until recently, but because of moving too far away from the base it became detached.
The landform in question is an ox-bow lake. This is a lake that has a short lifespan, and it usually has a half-circular shape, being just a few meters away from the river from which it formed. Initially, the ox-bow lake was actually part of the river and its meandering, but as the erosion was moving the water further and further away from the base of the river bed, the water was moving harder and harder, so naturally, the water moves in a direction where it is easier to do so. Little by little, the river starts to move in another direction, closer to its base, and the part of the meander that went too far away gets detached, thus forming an ox-bow lake.
