Answer:
Do you mean source of irrigation water?
Explanation:
The main sources for irrigation water are groundwater from wells, surface water, drainage ponds, rain and municipal water.
It was to stop the flow of refugees into West Berlin
The correct answer would be D His work on gravity.
He developed the theory of universal gravity which we know as the inverse square law. He thought of 3 laws of motion and proved them by using mathematics. he investigated the planets movements.