**Core Concept**
Digitalis toxicity, also known as digoxin toxicity, occurs when the levels of digitalis glycosides, such as digoxin, exceed the therapeutic range in the body. This can lead to various cardiac and neurological symptoms due to the inhibition of the sodium-potassium ATPase pump, resulting in increased intracellular sodium and calcium levels.

**Why the Correct Answer is Right**
Digitalis toxicity is characterized by a range of clinical manifestations, including nausea, vomiting, visual disturbances, and cardiac arrhythmias. One of the key features of digitalis toxicity is the appearance of a characteristic electrocardiographic (ECG) pattern, known as "digitalis effect" or "digitalis toxicity pattern," which includes a prolonged PR interval, widened QRS complex, and a characteristic "scooped" appearance of the P wave. This is due to the inhibition of the sodium-potassium ATPase pump, leading to increased intracellular calcium levels and enhanced automaticity of the cardiac pacemaker cells.

**Why Each Wrong Option is Incorrect**
**Option A:** While bradycardia is a common finding in digitalis toxicity, it is not the only option listed. Digitalis toxicity can also cause tachyarrhythmias, such as atrial fibrillation or ventricular tachycardia.

**Option B:** Hyperkalemia is not typically seen in digitalis toxicity. In fact, digitalis toxicity can cause hypokalemia due to increased potassium excretion in the urine.

**Option C:** This option is the correct answer, but since it's not provided, we'll move on.

**Option D:** While hypomagnesemia is not a direct effect of digitalis toxicity, it can contribute to the development of toxicity by increasing the sensitivity of the heart to digitalis.

**Clinical Pearl / High-Yield Fact**
A classic clinical sign of digitalis toxicity is the appearance of "yellow vision" or "greenish-yellow halos" around lights, which is due to the effects of digitalis on the retina.

**Correct Answer: B. Hyperkalemia is not typically seen in digitalis toxicity.**