**Core Concept**
Hyperkinetic disorder, also known as Attention Deficit Hyperactivity Disorder (ADHD), is a neurodevelopmental disorder characterized by excessive restlessness, impulsivity, and inattention. The core features of hyperkinetic disorder include symptoms of hyperactivity, inattention, and impulsivity, which can have a significant impact on a child's academic and social functioning.

**Why the Correct Answer is Right**
The correct answer to this question is not explicitly stated, but we can infer it based on the common characteristics of hyperkinetic disorder. Children with hyperkinetic disorder typically exhibit excessive motor activity, such as fidgeting, restlessness, or difficulty remaining seated. They may also have difficulty sustaining attention, following instructions, or completing tasks. Additionally, they may display impulsive behavior, such as interrupting others, blurting out answers, or difficulty waiting for their turn.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because sleep disturbances are a common comorbidity in children with hyperkinetic disorder. Children with ADHD often have difficulty falling asleep or staying asleep, which can exacerbate their symptoms.
**Option B:** This option is incorrect because emotional dysregulation is a common feature of hyperkinetic disorder. Children with ADHD may exhibit mood swings, irritability, or explosive behavior in response to frustration or stress.
**Option B:** This option is incorrect because social anxiety is a common comorbidity in children with hyperkinetic disorder. Children with ADHD may struggle with social interactions, have difficulty making friends, or experience anxiety in social situations.

**Clinical Pearl / High-Yield Fact**
It's essential to note that hyperkinetic disorder is a neurodevelopmental disorder with a strong genetic component. Children with a family history of ADHD or other neurodevelopmental disorders are at higher risk of developing hyperkinetic disorder.

**Correct Answer:** None provided, as the question lacks a correct answer option.