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: Anatomy
Posterior boundary of carotid triangle is - 
Select and explain. 
A. Omohyoid superior belly, B. Sternocleidomastoid posterior margin, C. Digastric posterior belly, D. Sternocliedomastoid anterior margin
D: Sternocliedomastoid anterior margin
Answer: D: Sternocliedomastoid anterior margin 
Explanation: Posterior boundry of carotid triangle is formed by anterior border of sternocleidomastoid.