**Core Concept**
ADHD (Attention Deficit Hyperactivity Disorder) is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, and impulsivity in children. It is a common condition affecting 5-10% of children worldwide.

**Why the Correct Answer is Right**
The child's symptoms of restlessness, inattentiveness, and desire to play outside are classic signs of ADHD. Children with ADHD often have difficulties sustaining attention in tasks, following instructions, and controlling their impulses. They may also exhibit physical symptoms such as fidgeting, squirming, or feeling restless. The child's age and symptoms suggest a need for a comprehensive evaluation by a pediatrician or a child psychiatrist to rule out other conditions and confirm the diagnosis of ADHD.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because ADHD is not caused by poor parenting or lack of discipline. While behavioral modifications and parenting strategies can be helpful, they are not the primary treatment for ADHD.

**Option B:** This is incorrect because there is no evidence that excessive screen time or video games cause ADHD. While excessive screen time can exacerbate symptoms of inattention and hyperactivity, it is not a primary cause of the condition.

**Option C:** This is incorrect because medication is just one aspect of treatment for ADHD. A comprehensive treatment plan typically includes behavioral therapy, lifestyle modifications, and education to help the child manage their symptoms.

**Option D:** This is incorrect because a diagnosis of ADHD requires a comprehensive evaluation by a qualified professional, including a thorough medical and psychological history, physical examination, and behavioral observations.

**Clinical Pearl / High-Yield Fact**
ADHD is a neurodevelopmental disorder that affects 5-10% of children worldwide. Early diagnosis and treatment can significantly improve symptoms and outcomes for children with ADHD.

**Correct Answer:** D.