Final answer:
The connection between overpopulation, drought, and warfare is the competition for limited resources.
Step-by-step explanation:
The connection between overpopulation, drought, and warfare lies in the competition for limited resources. As the population grows, the demands for land, water, food, and energy also increase, leading to a strain on these resources and creating competition among individuals and nations. In times of scarcity, conflicts over resources can arise, and warfare can break out.