**Core Concept**
Conduct disorder (CD) is a behavioral and emotional disorder characterized by persistent patterns of violation of social norms, including aggression, deceit, and destruction of property. While it affects both genders, the expression of symptoms differs, with boys more frequently exhibiting physical aggression.

**Why the Correct Answer is Right**
In conduct disorder, physical aggression is most commonly seen in boys, not girls. Girls with CD are more likely to display emotional bullying, running away from home, and high-risk sexual behaviors. The pathophysiology involves dysregulation of frontal lobe function and impaired emotional control, but gender-specific behavioral manifestations are well-documented. Physical aggression is a core feature in boys but is less frequently reported in girls with CD.

**Why Each Wrong Option is Incorrect**
Option A: Runaway behavior is more common in girls with conduct disorder, reflecting emotional distress and family conflict.
Option B: High-risk sexual behavior is a well-documented feature in female patients with CD, linked to poor emotional regulation and peer influence.
Option D: Emotional bullying is a hallmark of girls with CD, often manifesting as verbal or social manipulation rather than physical acts.

**Clinical Pearl / High-Yield Fact**
In conduct disorder, girls are more likely to engage in emotional and relational aggression (e.g., bullying, manipulation) than physical aggression. This distinction is crucial for accurate diagnosis and tailored intervention.

✓ Correct Answer: C. Physical aggression