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
[{'content': "Features of superior canal dehiscence are -a) Positive Romberg's signb) Positive Tullio's phenomenonc) Positive Hennebert's signd) Oscillopsiae) Positive Dix-Hallpike maneuver \nSelect and explain. \nA. c, B. d, C. ab, D. bd", 'role': 'user'}, {'content': 'Answer: D \nExplanation: In 1998, Lloyd minor and colleagues described sound and/or presssure induced vertigo associated with bony dehiscence of the\xa0superior semicircular canal.\n\nThird window effect takes place in case of dehiscent superior semicircular canal whereby the dehiscent part of semicircular\xa0canal acts as a third window of inner ear. As a result, endolymph within the labyrinthine system continues to move in relation\xa0to sound or pressure changes which causes activation of the vestibular system.', 'role': 'assistant'}]