Exp) Option c is the correct answer. 

The Earth’s atmosphere is not just composed of gases but also holds various solid particles such as dust, sea salt, pollen,etc. These particles are known as aerosols, and they play an essential role in weather phenomena such as cloud formation, precipitation, and visibility.

Statement I is correct.  Dust particles are more concentrated in subtropical and temperate regions due to the presence of dry winds. These regions often experience arid and semi-arid climates, where the lack of vegetation and strong winds promote the suspension of dust particles in the atmosphere. Deserts such as the Sahara, Thar, and Arabian Desert, all located in subtropical zones, are prime examples of major dust sources. In contrast, equatorial regions are humid and vegetated, which suppresses dust through rainfall and plant cover, while polar regions are cold and icy, limiting dust production.

Statement II is incorrect.  Dry winds are prevalent in subtropical and temperate regions, and these winds are precisely the reason dust concentration is higher in these areas. In the subtropics, for example, descending air from the subtropical high-pressure belts results in dry and stable conditions, which are associated with low humidity and dusty environments.

Source:https://ncert.nic.in/textbook/pdf/kegy207.pdf