**Core Concept:** Developmental milestones are significant changes in a child's behavior or abilities that occur at specific ages. They are used to assess a child's cognitive, motor, and social-emotional development.

**Why the Correct Answer is Right:** The correct answer, **Option D (18 months)**, represents the age at which a child typically develops the ability to recognize their age, gender, and name. This milestone is known as the **"Self-Knowledge"** milestone and is considered an important milestone in a child's cognitive development.

**Why Each Wrong Option is Incorrect:** Let's discuss the reasons behind incorrect options:

A. **12 months:** This option is too early for the "Self-Knowledge" milestone, which usually emerges around 18 months of age.
B. **36 months:** This option is too late, as the milestone should have been achieved by 18 months.
C. **60 months (5 years):** Although a child may have various developmental milestones by 5 years, the "Self-Knowledge" milestone is specific to 18 months, not 5 years.

**Clinical Pearl:** Assessing a child's developmental milestones is essential for early detection and intervention in case of developmental delays. Parents and healthcare providers should regularly monitor a child's progress and consult a pediatrician if there are concerns about their development.

**Correct Answer:** **Option D (18 months)** represents the typical age at which a child demonstrates the "Self-Knowledge" milestone, including recognizing their age, gender, and name, as well as drawing a circle and building a tower of nine cubes.