## Core Concept
The term "youth" generally refers to the period of life when an individual transitions from childhood to adulthood. This phase is characterized by significant physical, psychological, and social changes. The World Health Organization (WHO) defines youth as those between the ages of 15 and 24 years.

## Why the Correct Answer is Right
The correct answer, , aligns with the WHO's definition of youth. This age range captures the critical period of transition from adolescence to adulthood, marked by exploration of identities, independence, and preparation for adult roles. The age range of 15 to 24 years is widely accepted in international contexts for statistical and programmatic purposes.

## Why Each Wrong Option is Incorrect
* **Option A:** This range is too broad and includes children and older adults, not specifically targeting the youth demographic.
* **Option B:** This range starts too early, including children who are not considered youth, and ends too early, excluding young adults.
* **Option D:** This range ends too late, extending beyond the typical definition of youth and into adulthood.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the definition of youth can vary slightly depending on the context or organization. However, the WHO's definition of 15-24 years is a commonly used benchmark. Understanding this age range is crucial for public health, education, and social programs targeting young people.

## Correct Answer: B. 15-24 years.