**Core Concept**
The question tests the understanding of pediatric growth and development, specifically the correlation between a child's height and birth weight at different ages. This concept is crucial in assessing the growth and development of children.

**Why the Correct Answer is Right**
The correct answer is based on the principle that a child's height is approximately double their birth weight at around 4 years of age. This is because, on average, a child's birth weight doubles by 4-5 months and triples by 12 months, with their height increasing accordingly.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately represent the age at which a child's height is double their birth weight.
**Option B:** This option is also incorrect as it does not align with the established growth pattern.
**Option D:** Similarly, this option does not correctly represent the age-height correlation.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that growth charts are essential tools in pediatric care, helping to track the development of children and identify any potential growth or developmental issues early on.

**Correct Answer:** C. 4 years