**Core Concept**
Brugada syndrome is a genetic disorder that affects the heart's electrical system, leading to abnormal heart rhythms (arrhythmias). It is primarily characterized by distinctive electrocardiogram (ECG) changes.

**Why the Correct Answer is Right**
The hallmark ECG feature of Brugada syndrome is the presence of ST elevation in the right precordial leads (V1-V3). This is due to an abnormal functioning of the sodium channels in the heart, which leads to an abnormal repolarization of the cardiac action potential. The ST elevation is typically observed in the early repolarization phase of the cardiac cycle. The other ECG features of Brugada syndrome include a coved-type ST elevation and a saddleback appearance of the ST segment.

**Why Each Wrong Option is Incorrect**
* **Option B:** Prolonged PR interval is not a characteristic feature of Brugada syndrome. Instead, the PR interval is usually normal or even short.
* **Option C:** Prolonged QT interval is not a typical feature of Brugada syndrome. The QT interval might be normal or slightly shortened in these patients.
* **Option D:** Tall T waves can be seen in various cardiac conditions, but they are not a specific feature of Brugada syndrome.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize that Brugada syndrome can manifest with different ECG patterns, and some patients might not have the classic ST elevation in the right precordial leads. A family history of sudden cardiac death or the presence of other risk factors (such as a history of syncope or documented ventricular fibrillation) should prompt further investigation.

**✓ Correct Answer: A. ST elevation.**