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: Unknown
Sniff test is used in ? 
Select and explain. 
A. Facial nerve palsy, B. Vestibular nerve palsy, C. Phrenic nerve palsy, D. Occulomotor nerve palsy
C: Phrenic nerve palsy
Answer: C: Phrenic nerve palsy 
Explanation: Sniff testThe fluoroscopic'sniff test, also known as diaphragm fluoroscopy, is a quick and easy real time fluoroscopic assessment of diaphragmatic motor function (excursion).It is used most often to confirm absence of muscular contraction of the diaphragm during expiration in patients with phrenic nerve palsy or breathing difficulties following stroke.Chest radiograph demonstrating a newly elevated hemidiaphragm often precedes a sniff test.