The vast geographical feature which forms a border between nigeria, chad, cameroon and niger, is a__

The Answer is Lake.
This Vast geographical feature is also called "Chad Lake". There is a vast area which forms a border between Nigeria, chad, Cameroon and Niger is a lake.
Chad is an Area with four bioclimatic zones and in the world it is one of the 48 land-locked countries. The second largest lake in the west Africa is Lake Chad.

b: to eliminate competition from other farmers

to reform the distraught soviet union, the democratization of the communist party was promoted through party secretary mikhail gorbachev's policies of “perestroika” and “glasnost.” perestroika refers to the reconstruction of the political and economic system established by the communist party.