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
Greater vein of galen is formed by - 
Select and explain. 
A. Superior sagittal sinus with straight sinus, B. Inferior sagittal sinus with straight sinus, C. Internal cerebral veins, D. Basilar vein
C: Internal cerebral veins
Answer: C: Internal cerebral veins 
Explanation: Great cerebral vein of Galen is formed by the union of two internal cerebral veins.