This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Ciliary movement rate of nasal mucosa is: 
Select and explain. 
A. 1-2 mm/min, B. 2-5 mm/min, C. 5-10 mm/min, D. 10-12 mm/min
C: 5-10 mm/min
Answer: C: 5-10 mm/min 
Explanation: Nasal mucosa contains goblet cells responsible for secretion of mucosa. The cilia of nasal mucosa beat constantly at speed of 5-10 mm/minute and are in contact with serous layer of mucus which entraps the foreign bodies, allergens and carry it to nasopharynx. Beat frequency = 10 Hz Movement is metachronus (i.e. all cilia at right angle to the direction of flow are in the direction of flow while those in the direction of flow are slightly out of phase). Mucociliary clearance time = 5-20 mins. The pH of mucous blanket of nose is 7.