Which is the correct topographic difference between Bhangar and Khadar?

Correct answer: Bhangar is relatively higher old alluvium and Khadar is lower new floodplain

Bhangar and Khadar are two important alluvial surfaces of the northern plains. Bhangar is the older alluvium. It lies on relatively higher ground and is generally beyond the reach of ordinary annual floods. Khadar is the newer alluvium deposited in the lower floodplain by rivers during more recent floods. Because it is renewed more frequently, Khadar is often more fertile, though it can also face flooding. Therefore, option D gives the correct difference. Option A reverses both names and their relative positions, so it is incorrect. The other options describe unrelated landforms.

The easiest way to remember the distinction is old and high for Bhangar, and new and low for Khadar. River deposition is active in Khadar, while Bhangar represents an older terrace-like surface. This is a topographic as well as a geological difference: elevation and age change together in the usual textbook description. Neither unit is a coral island or a Deccan lava region. Thus option D is the only choice that correctly matches both the name and the characteristics.