Because of which one of the following factors, clouds do not precipitate in deserts?

Clouds do not precipitate in deserts primarily due to low humidity and the resulting lack of moisture. Deserts are characterized by extreme aridity where the amount of evaporation often greatly exceeds annual rainfall. In subtropical deserts, descending air from high-pressure cells is dry and stable, preventing the condensation of moisture into precipitation [2]. Even when clouds form, the low relative humidity in the surrounding air means there is insufficient water vapor to allow cloud droplets to grow large enough for gravity to overcome updrafts. Furthermore, the high temperatures in these regions increase the air's capacity to hold moisture without reaching saturation, and any falling rain often evaporates before reaching the ground (virga) due to the intense heat and dry air layers beneath the clouds.

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Hot Desert Biome > p. 15
2. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 7: Arid or Desert Landforms > Types of Desert > p. 67