Which reason best explains why areas of South and Southwest asia with arid climates aren't densely populated?

The arid climates contribute to low air quality from pollution.
Cities located in arid climates are negatively affected by floods from nearby rivers.
Monsoon rainfall produced in arid climates destroys settlements.
The arid climate cannot support farming.

The arid climate cannot support farming.

Are you sure?

My apologies for the confusion. I cannot guarantee that my response is accurate without more information. However, in general, an arid climate often poses challenges for agriculture due to lack of water and limited availability of suitable land for cultivation. This can be a significant factor in limiting population density in areas with arid climates. Other factors such as low air quality, floods, or monsoon rainfall can also play a role, but the lack of agricultural support in arid climates is usually a primary reason for lower population density.