**Core Concept**
The question is testing the knowledge of medications that can cause QT interval prolongation, a serious cardiac arrhythmia. QT interval prolongation is a condition where the time it takes for the heart's ventricles to prepare for a new contraction is lengthened, increasing the risk of a potentially life-threatening arrhythmia called Torsades de Pointes.

**Why the Correct Answer is Right**
The correct answer is a medication that has been implicated in causing QT interval prolongation, particularly in vulnerable populations such as premature babies. This is due to the medication's effects on the cardiac ion channels, specifically the potassium channels (IKr), which can lead to a prolongation of the QT interval.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a well-documented cause of QT interval prolongation.
**Option B:** This option is incorrect because it is not commonly associated with QT interval prolongation in premature babies.
**Option C:** This option is incorrect because it has a different mechanism of action that does not involve QT interval prolongation.

**Clinical Pearl / High-Yield Fact**
It's essential to be aware of medications that can cause QT interval prolongation, especially in vulnerable populations such as premature babies, and to monitor their ECGs closely for any signs of arrhythmias.

**Correct Answer:** C. Flecainide