This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharyngeal Arches, Subject name: Anatomy
Posterior fontanelle fuses at ? 
Select and explain. 
A. 2-3 months, B. 12 months, C. 18-24 months, D. 36 months
A: 2-3 months
Answer: A: 2-3 months 
Explanation: 2-3 months -fusion of posterior fontanelle. 18-24 months - fusion of anterior fontanelle.