The correct answer is (a) They both show the constructive power of erosion.
Oxbows and loess both show similarity as they both show the constructive power of erosion. An oxbow lake starts as a curve in a river. Oxbows are formed where the river often empties into another water body. They are found in the low lying area. A loess is a sediment which is formed by the accumulation of the wind blown silt. They can experience a erosion rate of 2.5 kg /m² per year.
