This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Mastoid fontanelle closes by 
Select and explain. 
A. 1-3 months, B. 3-6 months, C. 11-12 months, D. 18-24 months
C: 11-12 months
Answer: C: 11-12 months 
Explanation: Closure of Fontanelles:1. Anterior fontanelle by 18 months2. Posterior fontanelle by 2-3 months3. Sphenoidal fontanelle by 2-3 months and 4. Mastoid fontanelle by 12 months Reference: Chourasia; 6th edition; 12th page