**Core Concept**
Reticulocytes are immature red blood cells that circulate in the blood for a short period before maturing into adult red blood cells. In newborns, the reticulocyte count is typically elevated due to the rapid growth and development of the hematopoietic system.

**Why the Correct Answer is Right**
In newborns, the reticulocyte count is usually higher than in adults due to the increased demand for red blood cells to support growth and development. This is reflected in the higher reticulocyte count observed in newborns, which is often above 5-6%. The elevated reticulocyte count in newborns is a normal physiological response to the increased demand for red blood cells.

**Why Each Wrong Option is Incorrect**
**Option A:** A reticulocyte count of 1-2% is typically considered normal in adults, not newborns.
**Option B:** A reticulocyte count of 10-15% is not typically seen in newborns and may indicate a pathological condition.
**Option C:** A reticulocyte count of 0-1% is considered low and may indicate a hematological disorder.

**Clinical Pearl / High-Yield Fact**
Newborns have a higher reticulocyte count due to the rapid growth and development of the hematopoietic system, which is essential for their development.

**Correct Answer: D. 5-6%**