They are bulb-like structures at the tip of the frontal lobe where the olfactory nerves begin. (Ans A)
Explanation:
Olfactory receptors which are also known as smell receptor, and present in the cell membrane of olfactory receptor neurons. They are the proteins which are capable of binding with odour molecules which play an important role in the sense of smell.
Each receptor of olfactory cell contains a single external process which extends to the surface which is found in the epithelium, and gives rise long, slender extensions know as cilia. Mucus of the nasal cavity covered the cilia, and facilitating the detection of odour molecules.
