**Core Concept**
The most common cause of seizures in newborns is related to the abnormal electrical activity in the brain, which can be caused by various factors such as infections, metabolic disorders, or structural abnormalities. This condition is often referred to as neonatal seizures.

**Why the Correct Answer is Right**
Neonatal seizures are most commonly caused by hypoxic-ischemic encephalopathy (HIE), which occurs due to a lack of oxygen and blood flow to the brain. This can happen during delivery or shortly after birth, leading to brain damage and abnormal electrical activity. The lack of oxygen triggers a cascade of events, including the release of excitatory neurotransmitters, such as glutamate, which can lead to neuronal depolarization and seizure activity.

**Why Each Wrong Option is Incorrect**
* **Option A:** Infections, such as meningitis or encephalitis, can cause seizures in newborns but are not the most common cause.
* **Option B:** Metabolic disorders, such as hypoglycemia or hyperbilirubinemia, can also cause seizures in newborns but are not the most common cause.
* **Option C:** Structural abnormalities, such as congenital malformations or brain tumors, are rare causes of seizures in newborns.

**Clinical Pearl / High-Yield Fact**
Hypoxic-ischemic encephalopathy (HIE) is the most common cause of seizures in newborns, and prompt recognition and treatment are crucial to prevent long-term neurological damage.

**Correct Answer: A. Hypoxic-ischemic encephalopathy.**