The correct answer is A. Bhangar.
Bhangar is a type of old alluvium that is found in the Indo-Gangetic Plain. It is a relatively stable deposit that is composed of silt and clay. Bhangar is often used for agriculture, as it is a fertile soil.
Khadar is a type of new alluvium that is found in the Indo-Gangetic Plain. It is a relatively young deposit that is composed of sand and gravel. Khadar is often used for agriculture, as it is a fertile soil.
Tertiary is a geological period that lasted from about 66 million years ago to about 2.5 million years ago. It is divided into the Paleogene and Neogene epochs. The Tertiary period is characterized by the rise of mammals and the extinction of dinosaurs.
Quaternary is a geological period that began about 2.5 million years ago and continues to the present day. It is divided into the Pleistocene and Holocene epochs. The Quaternary period is characterized by the Ice Age and the rise of humans.
In conclusion, the old alluvium is known as Bhangar. It is a relatively stable deposit that is composed of silt and clay. Bhangar is often used for agriculture, as it is a fertile soil.