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: Dental
On microscopic examination enamel rods have: 
Select and explain. 
A. Key hole appearance in cross-section, B. Paddle appearance in cross-section, C. Lanullate appearance in cross-section, D. None of the above
A: Key hole appearance in cross-section
Answer: A: Key hole appearance in cross-section 
Explanation: Enamel rods appear in cross section as keyholes (or) fish scales (or) staggered arches (or) stacked arches.