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
The floor of the fourth ventricle contains all except - 
Select and explain. 
A. Abducent nucleus, B. Facial nucleus, C. Dorsal vagal nucleus, D. Hypoglossal nucleus
B: Facial nucleus
Answer: B: Facial nucleus 
Explanation: Nuclei in the floor of 4th ventricle

Abducent nucleus lies below facial colliculus.
Vestibular nuclei below vestibular area.
Dorsal nucleus of vagus below vagal triangle and hypoglossal nucleus below the hypoglossal triangle.

Option 'b' requires some explanation

The facial nerve is present on the floor of the 4th ventricle at facial colliculus. But the facial nucleus is not present in the floor of the 4th ventricle.