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
True about 4thventricle is- 
Select and explain. 
A. Rhomboid fossa forms floor, B. Choroid plexus lies at its floor, C. Connection between two cerebral hemispheres, D. Lies inferior to inferior cerebellar peduncle
A: Rhomboid fossa forms floor
Answer: A: Rhomboid fossa forms floor 
Explanation: A i.e., Rhomboid fossa forms the floor