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
Which of the following veins crosses perpendicularly the superficial surface of the sternocleidomastoid surface directly beneath the platysma muscle? 
Select and explain. 
A. Retromandibular, B. Anterior jugular, C. Posterior auricular, D. External jugular
D: External jugular
Answer: D: External jugular 
Explanation: The external jugular vein crosses perpendicularly the superficial surface of the sternocleidomastoid muscle directly under the platysma muscle. The anterior jugular descends near the median line. The posterior auricular joints the retromandibular to form the external jugular. The internal jugular runs in the carotid sheath deep to the sternocleidomastoid muscle.