This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
[{'content': 'All the following are boundaries of carotid triangle except \nSelect and explain. \nA. Anterior belly of Digastric, B. Posterior belly of Digastric, C. Superior belly of Digastric, D. Anterior margin of Sternocleidomastoid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Carotid Triangle Boundaries Anterosuperior: Posterior belly of the digastric muscle; and the stylohyoidAnteroinferior: Superior belly of the omohyoidPosteriorly: Anterior border of the sternocleidomastoid muscleReference: Chourasia; 6th edition; 98th page', 'role': 'assistant'}]