**Core Concept:** The question refers to the definition of adolescence, which is a stage of human development between childhood and adulthood. In medical context, it is crucial to understand the time frame of adolescence as it impacts various aspects of health care, including growth, puberty, mental health, and disease susceptibility.

**Why the Correct Answer is Right:** The correct answer, **D**, refers to the World Health Organization (WHO) definition of adolescence as "the stage of human development between 10 and 19 years of age." This definition is widely used globally due to the WHO's global influence and the need for standardization across healthcare systems.

**Why Each Wrong Option is Incorrect:**
A. **Option A (12-19 years):** This option is too broad. While it is a part of adolescence, it doesn't encompass the complete age range according to the WHO definition.
B. **Option B (10-25 years):** This option is too narrow. The WHO definition covers the age range from 10 to 19 years, not including the early childhood (0-9 years) and adulthood (20-29 years).
C. **Option C (puberty to early 30s):** This option is too broad, including not only adolescence but also the transition to adulthood and early 30s, which is not the WHO definition.

**Clinical Pearl / High-Yield Fact:** The term "puberty" is often used interchangeably with "adolescence" in the medical literature. However, the WHO definition helps standardize the concept globally, ensuring consistency in healthcare research and practice concerning this critical stage of life development.