Solution:Concept: Nasal cavity is an air-filled, hollow, and larger space present above the nose and in the middle of the face for the exchange of gasses in and out of the body. It has two parts: fossa, and nasal passage. The cavities are produced by the extinction of two nostrils, which is divided by nasal septum. It is found in the upper region of the respiratory system.
Functions of nasal cavity include: Nasal cavities act as a passage to pass the inhaled air. The air enters through nostrils, then goes to the nasal cavity front, then to the pharynx, then larynx and finally to lungs. The exhaled air moves out of the body through the nasal cavity. This nasal cavity has mucus which helps in purifying air. It acts as a sensory organ to recognize different smells as it has an olfactory odor. Due to the presence of larynx and pharynx, the nasal cavity is responsible for production of speech and producing sound.
Hence, air is the correct answer.