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': "Not a Boundary of Jackson's Triangle used in Tracheotomy \nSelect and explain. \nA. Suprasternal notch, B. Lower edge thyroid cartilage, C. Outer border of Sterno cleitomastoid, D. Inner border of  Sterno cleitomastoid", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]