**Core Concept**
The question pertains to the pharmacological management of mentally retarded children, specifically the choice of medication. This involves understanding the underlying pathophysiology of mental retardation and the role of pharmacotherapy in managing associated symptoms.

**Why the Correct Answer is Right**
Mentally retarded children often exhibit behavioral and psychiatric symptoms, such as aggression, hyperactivity, and attention deficit hyperactivity disorder (ADHD). Medications like **Risperidone** and **Olanzapine** are commonly used to manage these symptoms due to their efficacy in reducing agitation and aggression. These atypical antipsychotics work by **blocking dopamine D2 receptors** in the mesolimbic pathway, which is involved in the regulation of motor activity and emotional responses.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify a medication commonly used in the treatment of mentally retarded children. Other medications may be used, but the question seems to be asking for a specific drug.
**Option B:** This option is incorrect as it does not specify a medication commonly used in the treatment of mentally retarded children. Other medications may be used, but the question seems to be asking for a specific drug.
**Option C:** This option is incorrect as it does not specify a medication commonly used in the treatment of mentally retarded children. Other medications may be used, but the question seems to be asking for a specific drug.

**Clinical Pearl / High-Yield Fact**
Atypical antipsychotics like Risperidone and Olanzapine are preferred over typical antipsychotics due to their lower risk of extrapyramidal side effects and tardive dyskinesia.

**Correct Answer: D. Risperidone**