The river banks have attracted settlers from ancient times due to several reasons, which are summarized as follows:

a) Water is a basic natural resource:
- One of the primary reasons for settlers to be attracted to river banks is the availability of water, which is a basic necessity for human survival.
- Rivers serve as a natural source of freshwater, which is essential for drinking, cooking, and other domestic purposes.
- Settling near rivers ensured easy access to this vital resource, eliminating the need for long-distance travel or dependence on other water sources.

b) Rivers provide water for irrigation:
- Another significant advantage of settling near river banks is the availability of water for irrigation purposes.
- Rivers serve as a reliable source of water for agriculture, allowing settlers to cultivate crops and sustain a stable food supply.
- The fertile soil found along river banks, enriched by the sediment deposits carried by the river, further enhances the agricultural productivity of these regions.
- Irrigation systems can be easily set up using river water, ensuring consistent and controlled watering of crops, leading to improved yields.

c) Rivers provide facilities for inland navigation:
- River banks have always been an attractive settlement option due to the facilitation of inland navigation.
- Rivers provide a natural transportation network, enabling the movement of people and goods over long distances.
- Settling near rivers allowed for the development of trade and commerce, as goods could be transported easily and at a lower cost compared to land transportation.
- The presence of rivers also facilitated the establishment of ports and harbors, further enhancing trade opportunities and economic growth.

d) All of these:
- The correct answer choice is option 'D' because all the mentioned reasons - the availability of water as a natural resource, water for irrigation, and facilities for inland navigation - collectively make river banks highly attractive for settlers from ancient times.
- The combination of these factors provided settlers with the necessary resources for survival, agricultural productivity, and economic prosperity, making river banks ideal locations for human settlements throughout history.