**Core Concept:** The development of gender identity in children is a complex process involving genetic, neurological, and social factors. The concept of gender identity refers to an individual's subjective sense of their own gender, which may differ from their assigned gender at birth.

**Why the Correct Answer is Right:** A child's ability to identify their own gender typically develops by around 2 to 3 years of age. This process is known as the "gender identity formation" stage of gender development. In this stage, children begin to differentiate between male and female traits and characteristics, and start to develop a sense of their own gender identity.

**Why Each Wrong Option is Incorrect:**

A. 3-4 years: While this age range is involved in gender identity development, the correct answer is earlier, around 2-3 years.
B. 5 years: This is slightly later than the correct answer, as children typically develop gender identity before the onset of puberty.
C. 7 years: This age is associated with the onset of puberty and the development of gender role behavior, not gender identity formation.
D. 10 years: This is too late for gender identity formation, which occurs earlier in childhood.

**Clinical Pearl / High-Yield Fact:** Identifying an individual's gender identity is crucial for providing appropriate support, care, and treatment. Providers need to respect a child's expressed gender identity and follow it throughout their development, considering both biological and social factors.

**Correct Answer:** . 2-3 years