Which of the following was the most important development that cause people to shift from hunter gatherer societies to agriculture settlements more than 5000 years?

The most important development was  the use of flood plains and irrigation
Agricultural settlements require the society to stay within one place and produce their own food by leveraging all the resource in that place.
Food plains are crucial because it contains high-nutrition soil that provide enough foods for the plants to grow while irrigation is crucial so the society could provide enough water supply to sustain their crops.

The answer is b im not sure 

Answer( solar wind );