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: Ophthalmology
Corneal endothelium is embryologically derived from: 
Select and explain. 
A. Neural crest, B. Ectoderm, C. Mesoderm, D. Endoderm
A: Neural crest
Answer: A: Neural crest 
Explanation: A. i.e. Neuroectoderm