**Core Concept**
The patient's presentation suggests a complication of myocardial infarction leading to a life-threatening condition characterized by impaired cardiac function, hypotension, and electromechanical dissociation. This condition is associated with a high mortality rate if not promptly recognized and treated.

**Why the Correct Answer is Right**
The patient's clinical presentation, including pericardial friction rub, pleuritic chest pain, and marked hypotension, is suggestive of Dressler's syndrome or post-myocardial infarction syndrome. However, the development of electromechanical dissociation (EMD) and marked hypotension indicates a progression to cardiac tamponade, a condition where fluid accumulates in the pericardial sac, compressing the heart and impeding its function. The tension of the jugular veins is a classic sign of cardiac tamponade.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Dressler's syndrome, although a possible diagnosis, does not account for the sudden development of hypotension and electromechanical dissociation.

**Option B:** This option is incorrect because cardiac rupture would typically present with a more sudden and severe presentation, including a large pericardial effusion and a history of recent trauma or increased intrathoracic pressure.

**Option C:** This option is incorrect because cardiogenic shock would not typically present with electromechanical dissociation, which suggests a mechanical obstruction to cardiac function.

**Clinical Pearl / High-Yield Fact**
In cases of suspected cardiac tamponade, it is essential to recognize the clinical signs, including jugular venous distension, hypotension, and muffled heart sounds, and promptly perform an echocardiogram to confirm the diagnosis.

**Correct Answer: C. Cardiac tamponade**