**Core Concept**
Irreversible injury in myocardium, also known as necrosis, occurs due to prolonged ischemia, which disrupts the cellular energy production and leads to cellular death. This type of injury is characterized by the loss of cellular membrane integrity and the release of intracellular contents into the surrounding tissue.

**Why the Correct Answer is Right**
The correct answer is related to the concept of ischemia-reperfusion injury, where the myocardium is subjected to a prolonged period of ischemia, followed by reperfusion. This leads to the formation of reactive oxygen species (ROS) and the activation of various cellular pathways that ultimately result in cell death. The ischemic threshold is a critical concept here, where the myocardium is more susceptible to irreversible injury at a certain duration of ischemia. In the human heart, irreversible injury typically occurs after 20-30 minutes of ischemia.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the duration of ischemia, which is a critical factor in determining the extent of myocardial injury.
* **Option B:** This option is incorrect because it refers to reversible injury, which occurs at shorter durations of ischemia and is characterized by the preservation of cellular membrane integrity.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the duration of ischemia is a critical factor in determining the extent of myocardial injury. A duration of 20-30 minutes is generally considered the threshold for irreversible injury, beyond which the myocardium is more susceptible to cell death.

**Correct Answer:** C.