**Core Concept**
The growth pattern of a child is influenced by various factors, including genetics, nutrition, and overall health. At birth, a child's height is approximately 50 cm (20 inches), and it increases significantly during the first two decades of life. The growth rate is not constant, and there are distinct periods of rapid growth and slower growth.

**Why the Correct Answer is Right**
During the first year of life, a child grows rapidly, and their height increases by approximately 25 cm (10 inches). This growth rate slows down after the first year, but it accelerates again during the growth spurt around 6-8 years of age. By the age of 12-14, children typically experience another growth spurt, which is often accompanied by a significant increase in height. By the age of 12-14, girls and boys typically double their birth height. This growth pattern is influenced by the release of growth hormone, which stimulates the growth plates in the long bones to produce new bone tissue.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because the growth rate is not consistent throughout childhood, and it takes longer than a few years for a child to double their birth height.
* **Option B:** This is incorrect because the growth spurt around 6-8 years of age is significant, but it does not result in doubling of birth height.
* **Option C:** This is incorrect because the growth rate slows down after the first year, and it takes longer than 2-3 years for a child to double their birth height.

**Clinical Pearl / High-Yield Fact**
The growth rate of children is influenced by various factors, including genetics, nutrition, and overall health. A child's growth pattern can be affected by conditions such as growth hormone deficiency, Turner syndrome, or hypothyroidism.

**Correct Answer:** C. 12-14 years.