The correct answer is D) Rivers provided a source of water to irrigate fields.
Rivers helped ancient peoples to increase food supplies in that rivers provided a source of water to irrigate fields.
This was an important moment in the history of ancient civilizations when ancient people learned how to control the flooding of the rivers to use the water for irrigation purposes and grow more and better crops. The flooding of the rivers produced fertile soil that facilitated farming and good crops.
That was part of the success of ancient civilizations such as Sumeria, that settled in the middle of the Euphrates and Tigris Rivers, or the ancient Egyptians that settled along the Nile River, or the Indus River civilization that settled next to the Indus River.