**Core Concept**
The question is testing the understanding of extrapyramidal side effects (EPS) of antipsychotic medications. EPS are a group of movement disorders associated with the blockade of dopamine D2 receptors in the basal ganglia. The severity of EPS varies among different classes of antipsychotics.

**Why the Correct Answer is Right**
Haloperidol is a typical antipsychotic with a high potency and selective blockade of D2 receptors. This high affinity for D2 receptors leads to a higher incidence of EPS. In contrast, Clozapine is an atypical antipsychotic with a lower affinity for D2 receptors and a higher affinity for serotonin 5-HT2 receptors. This unique pharmacological profile makes Clozapine less likely to cause EPS.

**Why Each Wrong Option is Incorrect**
* **Option A:** Haloperidol has a high potency and selective blockade of D2 receptors, making it more likely to cause EPS.
* **Option B:** Risperidone is an atypical antipsychotic but has a higher affinity for D2 receptors compared to Clozapine, increasing the risk of EPS.
* **Option D:** Olanzapine is another atypical antipsychotic but has a higher incidence of EPS compared to Clozapine due to its higher affinity for D2 receptors.

**Clinical Pearl / High-Yield Fact**
Atypical antipsychotics like Clozapine are preferred in patients with a high risk of EPS, such as elderly patients or those with a history of movement disorders. These medications have a lower risk of EPS but may have other side effects like weight gain and metabolic disturbances.

**Correct Answer:** C. Clozapine has the least extrapyramidal side effect.