**Core Concept**
The myocardial isoenzyme of creatine kinase (CK) is a crucial biomarker for diagnosing myocardial infarction. CK is an enzyme found in various tissues, including the heart, brain, and skeletal muscle, but the myocardial isoenzyme, specifically CK-MM (also known as CK-BB), is predominantly expressed in the heart.

**Why the Correct Answer is Right**
The myocardial isoenzyme of CK, specifically CK-MB (also known as CK-MM), is released into the bloodstream following myocardial infarction due to muscle damage. This enzyme is more specific to the heart than other forms of CK, making it a valuable diagnostic tool for detecting cardiac damage. CK-MB is cleared from the blood within 72 hours, whereas other CK isoenzymes, such as CK-MM, persist in the blood for longer periods.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because CK-BB is primarily found in the brain and not specific to the heart.
**Option B:** This option is incorrect because CK-MM is a muscle-specific isoenzyme, predominantly found in skeletal muscle, and not specific to the heart.
**Option C:** This option is incorrect because CK-MB is indeed the correct answer, but CK-MM is often confused with CK-MB due to similar nomenclature.

**Clinical Pearl / High-Yield Fact**
It's essential to note that CK-MB is not entirely specific to myocardial infarction, as it can also be elevated in other conditions, such as cardiac trauma, cardiac surgery, or significant muscle damage. However, in the context of myocardial infarction, CK-MB is a valuable diagnostic marker.

**Correct Answer: C. CK-MB (Creatine Kinase-Myocardial Band)**