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: Anatomy
In the skull all are true except 
Select and explain. 
A. The sutures are all fibrous joints, B. The coronal suture separates the frontal from the parietal bones, C. The posterior fontanelle usually closes 18 months after birth, D. After middle age cranial sutures begin to ossify from cranial surface
C: The posterior fontanelle usually closes 18 months after birth
Answer: C: The posterior fontanelle usually closes 18 months after birth 
Explanation: Posterior fontanelle usually closes between 3rd and 6th months after birth.