This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Subject name: Ophthalmology
Smooth muscle of the IRIS is developed from- 
Select and explain. 
A. Surface Ectoderm, B. Mesoderm, C. Neural Crest, D. Neural Ectoderm
D: Neural Ectoderm
Answer: D: Neural Ectoderm 
Explanation: Ans- D. Neuroectoderm forms iris muscles. Mesoderm gives rise to blood vessels and choroid Sphicter papillae and dilator papillae are smooth muscles of iris which are developed from neuroectoderm. Sphincter papillae - a circular bundle of smooth muscles running around the pupillary margin- causes constriction of the pupil. Dilator papillae- arranged radically near the root of the iris,causes dilation of the pupil.