**Core Concept:** Dyslexia is a neurodevelopmental disorder characterized by difficulties with accurate and/or rapid word reading, despite having normal intelligence and adequate exposure to written language. It is a common language-based disorder affecting approximately 5-10% of the population.

**Why the Correct Answer is Right:** The correct answer, option D (Dyslexia), is a disorder that affects the brain's ability to process written language, causing issues with reading, spelling, and writing skills. In this case, the child exhibits symptoms such as difficulty in expressing himself in writing, making frequent spelling mistakes, not following instructions, and having trouble waiting his turn during play. These symptoms align with the core characteristics of dyslexia.

**Why Each Wrong Option is Incorrect:**

A. This option does not specifically target the symptoms described in the question, focusing on other developmental disorders or conditions unrelated to written language processing.
B. Although the child might have difficulty with tasks that involve written language, this option does not cover the full range of symptoms mentioned, such as trouble following instructions and waiting turns.
C. This option focuses on language impairments, but does not address the specific challenges with written language processing described in the question.

**Clinical Pearl:** Dyslexia typically develops in childhood and can be associated with other co-occurring conditions like ADHD, dysgraphia, or developmental coordination disorder. Early identification and intervention can significantly improve outcomes for affected individuals.

**Correct Answer:** Dyslexia