In the given diagram, the question asks which lettered area would erosion most likely change the shapes of the riverbed.

Option 1 - Area A: This area appears to be relatively flat and doesn`t show any significant changes in the riverbed`s shape. Therefore, erosion is unlikely to have a significant impact on the riverbed in this area.

Option 2 - Area B: This area is where erosion is most likely to change the shape of the riverbed. It can be observed that the river is narrow, which indicates that the water is flowing through a confined space. Erosion in this area can lead to the widening and deepening of the riverbed, altering its shape.

Option 3 - Area C: This area shows a wider section of the river with a more gentle slope. Erosion here may occur, but it is not expected to have a significant impact on changing the shapes of the riverbed.

Option 4 - Area D: This area shows a meandering pattern indicating a natural course of the river. Erosion may occur along the outer curve (concave bank) of the meander, but it is less likely to change the overall shape of the riverbed.

Therefore, the correct answer is option 2 - Area B,