**Core Concept**
Infantile spasms, also known as West syndrome, is a severe form of epilepsy that affects infants. The condition is characterized by a specific pattern of seizures, known as spasms, which can be associated with developmental delays and cognitive impairment. The treatment of infantile spasms typically involves medications that can help control the seizures and promote brain development.

**Why the Correct Answer is Right**
The drug of choice for infantile spasms is adrenocorticotropic hormone (ACTH), which is a hormone that stimulates the adrenal glands to produce cortisol. Cortisol has anti-inflammatory properties and can help reduce the severity of seizures in infantile spasms. ACTH is administered intramuscularly or subcutaneously, and its use is typically reserved for infants with infantile spasms who have not responded to other treatments. The mechanism of action of ACTH in infantile spasms is thought to involve the reduction of inflammation in the brain and the promotion of neuroplasticity.

**Why Each Wrong Option is Incorrect**
**Option A:** Vigabatrin is an antiepileptic medication that can be used to treat infantile spasms, but it is not the first-line treatment and is often reserved for patients who have not responded to ACTH.
**Option B:** Phenytoin is an antiepileptic medication that is commonly used to treat various types of seizures, but it is not effective in treating infantile spasms.
**Option C:** Valproate is an antiepileptic medication that can be used to treat a variety of seizure disorders, but it is not the preferred treatment for infantile spasms.

**Clinical Pearl / High-Yield Fact**
The diagnosis of infantile spasms is often challenging, and a high index of suspicion is required to identify the condition. The characteristic "salaam" or "jackknife" posture of infants with infantile spasms is a key clinical clue that can aid in diagnosis.

**Correct Answer:** C. ACTH (Adrenocorticotropic hormone)