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
Metopic suture usually disappears by 
Select and explain. 
A. 2 years, B. 8 years, C. 4 years, D. 6 years
A: 2 years
Answer: A: 2 years 
Explanation: Frontal bone ossifies in membrane.
It develops from 2 centres near frontal eminences, during 8th week of intrauterine life.
At birth, the bone is in 2 halves, separated in the midline by a suture, known as metopic suture, which soon starts to fuse.
It usually fuse and gets disappeared by 2 years of age.
The metopic suture occasionally persists in 3 to 8% of individuals.
Premature closure of metopic suture is known as metopic craniosynostosis, resulting in trigonocephaly - triangle shaped head.