what does the increase in incidents of polar bears visiting human settlements indicate

The correct answer is "limited prey is driving the bears to seek food in human settlements".
Due to the warming of the Arctic waters, the ice is melting, resulting in a serious decline of floating winter ice. Polar bears need these floating parts of ice to hunt, therefore this new situation limits the hunting opportunities of the bears. That is why polar bears are driven to human settlements to look for food. 

Where’s the selection?