**Core Concept**
The question is testing the knowledge of antimalarial drugs and their side effects, specifically their potential to cause neuropsychiatric reactions and convulsions. This is a common concern with certain antimalarial medications, particularly those that affect the central nervous system.

**Why the Correct Answer is Right**
The correct answer is likely Artemether, which is a derivative of artemisinin. Artemether is known to cause neuropsychiatric reactions, including dizziness, headache, and convulsions, due to its ability to cross the blood-brain barrier and affect the central nervous system. This is because artemether is metabolized to dihydroartemisinin, which activates the aryl hydrocarbon receptor (AhR) in the brain, leading to increased excitability and potential seizures.

**Why Each Wrong Option is Incorrect**
* **Option A:** Chloroquine is not typically associated with neuropsychiatric reactions or convulsions. While it can cause visual disturbances and other side effects, convulsions are not a common concern.
* **Option B:** Mefloquine is an antimalarial drug that can cause neuropsychiatric reactions, but it is not as strongly associated with convulsions as Artemether. Mefloquine can cause anxiety, depression, and psychosis, but seizures are relatively rare.
* **Option D:** Primaquine is not commonly associated with neuropsychiatric reactions or convulsions. It can cause hemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, but seizures are not a typical side effect.

**Clinical Pearl / High-Yield Fact**
When prescribing antimalarial medications, it's essential to be aware of their potential side effects, particularly those that can affect the central nervous system. This includes monitoring patients for signs of neuropsychiatric reactions, such as dizziness, headache, and convulsions, especially when using medications like Artemether.

**Correct Answer: C. Artemether**