Which of these innovations was spread to southern africa as a result of the bantu migrations? a.) gunpowder. b.) iron working. c.) crop rotation. d.) subsistence farming.

The correct option is D subsistence farming. One of the innovations spread to Southern Africa as the result of the migration of Bantu-speaking people, which was a series of migration of the proto-Bantu language speaking group from central Africa across the sub-Sahara Africa, was the introduction of new farming techniques.  

Agriculture and farming techniques improved thanks to the ability of Bantu-speakers to reproduce and expand more quickly, surviving thanks to the plants and animals spread and cultivated by them.

the answer is a) to be able to obey them.

ok sorry the answer is a. by their religion