**Core Concept**
The patient is experiencing a sudden drop in mean arterial pressure, elevated JVP, and has recently undergone CABG surgery. This clinical presentation is highly suggestive of cardiac tamponade, which can occur due to bleeding or hematoma accumulation in the mediastinum following cardiac surgery.

**Why the Correct Answer is Right**
Cardiac tamponade is characterized by increased pressure within the pericardial sac, leading to compression of the heart and reduction in cardiac output. In the post-CABG setting, this can be due to bleeding or hematoma accumulation in the mediastinum. Immediate re-exploration of the mediastinum is essential to identify and control the source of bleeding, which is the most critical step in managing cardiac tamponade. This procedure allows for surgical exploration, repair of any cardiac or mediastinal injuries, and evacuation of any accumulated fluid or blood.

**Why Each Wrong Option is Incorrect**

* **Option A:** PRBC Transfusion may be necessary to address any anemia or hypovolemia, but it will not address the underlying cause of the cardiac tamponade.
* **Option B:** Vasopressors and inotropes may be used to support blood pressure, but they do not address the root cause of the tamponade and may even worsen cardiac function.
* **Option D:** Intra-aortic balloon pump (IABP) may be used to support cardiac function in cases of cardiogenic shock, but it does not address the underlying cause of the tamponade and may not be effective in this setting.

**Clinical Pearl / High-Yield Fact**
In the post-CABG setting, a sudden drop in mean arterial pressure and elevated JVP should prompt immediate suspicion of cardiac tamponade. The key to management is prompt surgical re-exploration to identify and control the source of bleeding.

**✓ Correct Answer: C. Immediate re-exploration of the mediastinum**