What would have most likely driven members of the bantu migration from west africa to the east and south of the continent?

ANSWER:

The need for more fertile land would have driven members of Bantu from West Africa to the east and south of the continent.

EXPLANATION:

The initial homeland of Bantu people is eastern part of the Western Africa. Due to population growth, need for food increased. Bantu started to migrate to the places having vast cultivable and grazing lands. The 'Bantu migration' was directed towards the southern and eastern region where most of the 'Savannas' are located. The savannas had fertile land for agriculture, enough pasture for livestock and animals for hunting if needed. This was right environment for Bantu to migrate.

It's lithogenous i believe of course i looked it up.