Which factor contributed the most to he destruction of the southern buffalo herds?

The destruction of the southern Buffalo herds was the result of trainloads which included tourists who shoot bison for their pleasure and sport from trains as they passed the Plains. Bison also killed because the government gave the permit to kill, to make Native Indians weakened and suffer from starvation by destroying herds. Native Indians depended on the Bison for their meat, and skin for the cloth and shelter to keep them warm.

A: Trainloads of tourists killed buffalo purely for sport.