When does basiocciput fuses with basisphenoid

When does basiocciput fuses with
basisphenoid?
a) 18 to 22
b) 22 to 25
c) 14-16
d) 12-14
Correct Answer - A
Answer: A. 18 to 22
The basioccipital fuses with the basisphenoid at about 18 to 21
years