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
Which of the fontanelle is last to close? 
Select and explain. 
A. Posterior fontanelle, B. Anterior fontanelle, C. Mastoid fontanelle, D. Sphenoidal fontanelle
B: Anterior fontanelle
Answer: B: Anterior fontanelle 
Explanation: Time of closure of different fontanelle: Posterior fontanelle- 2 to 3 months after bih Anterior fontanelle- 10-24 months after bih Mastoid fontanelle- 6- 18 months after bih Sphenoidal fontanelle- 6months after bih Ref: Nelson's 20th edition, page 2793