## **Core Concept**
The question tests knowledge of cardiac enzyme release patterns following myocardial infarction (MI). After an MI, various cardiac enzymes are released into the bloodstream at different times, which helps in diagnosing and timing the MI.

## **Why the Correct Answer is Right**
The correct answer, **LDH (Lactate Dehydrogenase)**, appears last in the sequence of enzyme elevations following an MI. The sequence of enzyme release is generally as follows: Creatine Phosphokinase (CPK or CK) rises first, followed by Aspartate Aminotransferase (AST), then Lactate Dehydrogenase (LDH). LDH, particularly its isoenzyme LDH-1, peaks later than other enzymes, making it useful for diagnosing MI several days after the event.

## **Why Each Wrong Option is Incorrect**
- **Option A: CPK (Creatine Phosphokinase)**: This enzyme rises earliest after an MI, peaking within 24 hours, making it an early marker but not the last.
- **Option B: AST (Aspartate Aminotransferase)**: Also known as SGOT, it rises after CPK but before LDH, peaking around 48 hours post-MI.
- **Option C: Not provided**, assuming a placeholder.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is the timeline of cardiac enzyme elevation post-MI: CPK (within 4-6 hours, peaks at 24 hours), AST (rises within 24-48 hours), and LDH (rises within 24-72 hours, peaks at 3-6 days). This timeline helps in assessing the timing of the MI.

## **Correct Answer: D. LDH.**