The plain stretches across northern india and is home to one-tenth of the world’s population.
a. ganges
b. manchurian
c. north chinese
d. west siberian

a. Ganges

Explanation:

The Indo-Gangnetic plain (or Ganges plain) is an extensive and fertile plain region that encompasses most of northern India, the most populous areas of Pakistan, southern Nepal and the entire territory of Bangladesh. The region takes its name from the Indus and Ganges rivers, whose waters pass through it.

The plain limits to the north and east with the Himalayas, where the numerous rivers that cross the plain are born; to the south with the mountains of Vindhya and Satpura and the Chota Nagpur plateau and to the west with the Iranian plateau.

The region is one of the most populated on Earth, being home aproximately to some 900 million people, one tenth of the world's population.