Concept:An ox-bow lake is a U-shaped water body formed from a river meander.
Explanation:A river first develops a meander, which is a pronounced bend or curve in its course.
Over time, erosion and deposition make the meander loop wider and narrower at the neck.
During a flood or high discharge, the river may cut through the narrow neck, bypassing the loop.
The abandoned loop becomes cut off from the main river and forms an ox-bow lake.
Therefore, the meander is the primary and essential first stage in this sequence.
Answer:B. Meander