Dry point settlements are settlements that are located on higher ground within an area that is typically prone to flooding or has a high water table. These settlements are chosen specifically to avoid the negative impacts of water, such as damage to structures and the spread of waterborne diseases.

In the context of the given options, deserts, plateaus, and mountain regions are not typically associated with high water levels or flooding. Deserts are characterized by arid conditions and low precipitation, making them unlikely locations for dry point settlements. Plateaus are elevated flat areas, while mountain regions are characterized by steep slopes and high elevations, both of which are not typically associated with flooding.

On the other hand, deltas are landforms formed at the mouth of a river, where the river deposits sediment over time, creating a triangular or fan-shaped area. Deltas are often prone to flooding due to their location near the confluence of multiple rivers, and their low-lying nature makes them unsuitable for dry point settlements.

Therefore, the correct answer is option 4 - Deltas. Alert - correct answer should be option 1 - Deserts.