The correct option is
C Olfactory membrane
Bowman's glands are also known as olfactory glands. They are present in olfactory mucosa of nasal cavity beneath the olfactory epithelium. The olfactory glands contain a secretory duct. The olfactory membrane is located over thick connective tissue called lamina propria. The olfactory glands secrete a mucous substance that protects the nasal epithelium from getting dry out.
So, the correct answer is 'Olfactory membrane'.