Concept:Ancient settlements depended on river water for farming and survival.
Explanation:Early civilisations such as Mesopotamia, Egypt, Indus Valley, and China grew near rivers like the Tigris, Nile, Indus, and Huang He.
Rivers provided fertile soil and water for agriculture.
Since agriculture was the main occupation of early man, riverbanks became the natural choice for settlement.
Therefore, the reason clearly explains the assertion.
Answer:Both Assertion (A) and Reason (R) are true, and (R) is the correct explanation of (A).
Correct option: A.