The northern plain of india is also called the
plain

The Northern Plain of India is also called the Indo- Gangetic plain. It is located in the southern part of the Himalayan range. The plain is formed from the flood plains of three big river systems namely the Indus, the Ganga  and the Brahmaputra.

The soil  cover in the plain is rich and fertile, and water is found in plenty combined with a favorable climate for growing several major crops. It is one of the world's most intensely farmed areas and is thus very densely populated.

the answer is:

c. islam and christianity

explanation:

islam and christianity are widely practiced in africa. islam is practiced due to its spread from the middle east into africa, and christianity is practiced due to the colonization of africa by the british empire.