**Core Concept**
Acute pericarditis is characterized by inflammation of the pericardium, leading to chest pain and electrocardiographic (ECG) changes. The ECG in acute pericarditis typically shows widespread ST-segment elevation in multiple leads, often with a distinctive pattern.

**Why the Correct Answer is Right**
In acute pericarditis, the ST-segment elevation is usually concave upwards and not a straight line as seen in myocardial infarction. This is due to the diffuse pericardial inflammation causing a uniform increase in the voltage of the ECG. The ECG changes in acute pericarditis are often accompanied by a characteristic "sharply" elevated ST-segment, which is a key diagnostic feature.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because the ST-segment elevation in pericarditis is typically concave upwards, not flat or isoelectric.
**Option B:** This statement is incorrect because the ECG in pericarditis does not show reciprocal ST-segment depression as seen in myocardial infarction.
**Option C:** This statement is incorrect because the ECG in pericarditis does not show Q-waves as seen in myocardial infarction.

**Clinical Pearl / High-Yield Fact**
In acute pericarditis, the ECG changes can be remembered using the mnemonic "V2-V3" which stands for the leads that typically show ST-segment elevation. However, it's essential to remember that the ECG changes in pericarditis can be diffuse and involve multiple leads.

**Correct Answer: C. Q-waves are not a feature of acute pericarditis.**