**Core Concept**
The question tests the understanding of creatine kinase (CK) isoenzymes and their specificity in diagnosing myocardial infarction. CK is an enzyme found in various tissues, including the heart, brain, and skeletal muscle. The isoenzymes of CK are used to diagnose tissue-specific damage.

**Why the Correct Answer is Right**
CK-MB is the myocardial isoenzyme of CK that is most specific for myocardial infarction. This is because CK-MB is predominantly found in the heart muscle. When the heart muscle is damaged, as in a myocardial infarction, CK-MB is released into the bloodstream, making it a sensitive and specific marker for cardiac damage. The enzyme is composed of two subunits, M and B, which are coded by different genes. The MB fraction is the most cardiac-specific, as the MM fraction is found in skeletal muscle and the BB fraction in the brain.

**Why Each Wrong Option is Incorrect**
**Option A:** CK-BB is the brain-type isoenzyme of CK and is not specific for myocardial infarction. **Option C:** CK-MM is the skeletal muscle-type isoenzyme of CK and is also not specific for myocardial infarction. **Option D:** "All of the above" is incorrect because only CK-MB is specific for myocardial infarction.

**Clinical Pearl / High-Yield Fact**
CK-MB is a crucial diagnostic marker for myocardial infarction, especially when used in conjunction with other diagnostic tools like troponin levels and electrocardiogram (ECG) findings. It is essential to remember that elevated CK-MB levels can also be seen in other conditions, such as severe skeletal muscle damage, but in the context of chest pain and ECG changes, it is highly suggestive of myocardial infarction.

**✓ Correct Answer: B. CK-MB**