**Core Concept**
Closure of coronal sutures is a significant event in the process of cranial suture closure, which occurs in response to the increasing intracranial pressure and the decreasing growth rate of the skull. This process is essential for the development of the cranial vault and the reduction of intracranial pressure.

**Why the Correct Answer is Right**
The closure of coronal sutures typically begins at around 6 years of age. This is due to the increasing intracranial pressure and the decreasing growth rate of the skull, which leads to the fusion of the coronal sutures. The coronal sutures are the largest of the cranial sutures and are responsible for the growth of the frontal and parietal bones. As the growth rate slows down, the coronal sutures start to close, and this process is usually completed by the age of 18-25 years.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the closure of coronal sutures does not typically begin before the age of 6 years.
**Option B:** This option is incorrect because the closure of coronal sutures does not typically begin after the age of 10 years.
**Option C:** This option is incorrect because the closure of coronal sutures does not typically begin at birth.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the closure of coronal sutures is a gradual process that occurs over several years, and it's not a sudden event. This knowledge is crucial for diagnosing and managing conditions related to cranial suture closure, such as craniosynostosis.

**Correct Answer: C. 6 years.**