Air entering the lungs is
a)	Warm and filtered	b)	Contains only oxygen
c)	Cool and filtered	d)	Enriched with  and

(a)

Air entering the lungs is warm and filtered.

Nasal Cavity It is the first part of the respiratory system. It opens to the exterior through nostrils. The small hairs present in the cavity helps to filter the particles of dust and other foreign matter. The air in the nasal cavity gets warmed (because nasal cavity has very good blood supply) and moistened before it enters to the lungs