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: Unknown
All the following veins drain into internal jugular vein except 
Select and explain. 
A. Facial vein, B. Lingual vein, C. Retromandibular vein, D. Superior thyroid vein
C: Retromandibular vein
Answer: C: Retromandibular vein 
Explanation: Retromandibular vein
Internal Jugular vein

It is the continuation of sigmoid sinus
Tributaries of IJV

1. Inferior Petrosal sinus
2. Ferial
3. Lingual
4. Pharyngeal
5. Superior thyroid vein
6. Middle thyroid vein